Daniel Hackett - Academia.edu (original) (raw)
Papers by Daniel Hackett
The American journal of sports medicine, Jan 16, 2015
Intensive sport participation in childhood and adolescence is an established cause of acute and o... more Intensive sport participation in childhood and adolescence is an established cause of acute and overuse injury. Interventions and programs designed to prevent such injuries are important in reducing individual and societal costs associated with treatment and recovery. Likewise, they help to maintain the accrual of positive outcomes from participation, such as cardiovascular health and skill development. To date, several studies have individually tested the effectiveness of injury prevention programs (IPPs). To determine the overall efficacy of structured multifaceted IPPs containing a combination of warm-up, neuromuscular strength, or proprioception training, targeting injury reduction rates according to risk exposure time in adolescent team sport contexts. Systematic review and meta-analysis. With established inclusion criteria, studies were searched in the following databases: Cochrane Central Register of Controlled Trials, MEDLINE, SPORTDiscus, Web of Science, EMBASE, CINAHL, and...
Sports medicine (Auckland, N.Z.), Jan 31, 2016
Muscle dysmorphia (MD) is associated with a self-perceived lack of size and muscularity, and is c... more Muscle dysmorphia (MD) is associated with a self-perceived lack of size and muscularity, and is characterized by a preoccupation with and pursuit of a hyper-mesomorphic body. MD symptoms may hypothetically be more prevalent in bodybuilders (BBs) than in non-bodybuilder resistance trainers (NBBRTs). Our objective was to compare MD symptomatology in BBs versus NBBRTs and identify psychological and other characteristics associated with MD in these groups. We searched relevant databases from earliest record to February 2015 for studies examining MD symptoms in BBs and/or NBBRTs. Included studies needed to assess MD using a psychometrically validated assessment tool. Study quality was evaluated using an adapted version of the validated Downs and Black tool. We calculated between-group standardized mean difference (effect sizes [ESs]) and 95 % confidence intervals (CIs) for each MD subscale, and performed meta-analysis when five or more studies used the same MD tool. We also extracted dat...
International journal of rehabilitation research. Internationale Zeitschrift fur Rehabilitationsforschung. Revue internationale de recherches de readaptation, Jan 12, 2016
This systematic review with a meta-analysis of studies was carried out to evaluate the potential ... more This systematic review with a meta-analysis of studies was carried out to evaluate the potential of overwork weakness on the basis of grip strength of dominant and nondominant hands in individuals with Charcot-Marie-Tooth disease (CMT). Numerous electronic databases were searched from the earliest records to February 2016. Studies of any design including participants older than 18 years of age with a confirmed diagnosis of CMT that measured grip strength of both hands using dynamometric testing were eligible for inclusion. Of 12 593 articles identified following removal of duplicates, five articles fulfilled the criteria. A total of 166 participants, mostly with CMT1 or CMT2, were described from the studies included. Hand and finger pinch grip strength for the dominant compared with the nondominant hand was not statistically different. There is no definitive evidence that preferential use of the dominant hand in CMT impairs function relative to the nondominant hand. Thus, robust exe...
Sports medicine (Auckland, N.Z.), Jan 18, 2016
Sports medicine (Auckland, N.Z.), Jan 14, 2015
It remains unclear whether repetitions leading to failure (failure training) or not leading to fa... more It remains unclear whether repetitions leading to failure (failure training) or not leading to failure (non-failure training) lead to superior muscular strength gains during resistance exercise. Failure training may provide the stimulus needed to enhance muscular strength development. However, it is argued that non-failure training leads to similar increases in muscular strength without the need for high levels of discomfort and physical effort, which are associated with failure training. We conducted a systematic review and meta-analysis to examine the effect of failure versus non-failure training on muscular strength. Five electronic databases were searched using terms related to failure and non-failure training. Studies were deemed eligible for inclusion if they met the following criteria: (1) randomised and non-randomised studies; (2) resistance training intervention where repetitions were performed to failure; (3) a non-failure comparison group; (4) resistance training interven...
The American journal of sports medicine, Jan 16, 2015
Intensive sport participation in childhood and adolescence is an established cause of acute and o... more Intensive sport participation in childhood and adolescence is an established cause of acute and overuse injury. Interventions and programs designed to prevent such injuries are important in reducing individual and societal costs associated with treatment and recovery. Likewise, they help to maintain the accrual of positive outcomes from participation, such as cardiovascular health and skill development. To date, several studies have individually tested the effectiveness of injury prevention programs (IPPs). To determine the overall efficacy of structured multifaceted IPPs containing a combination of warm-up, neuromuscular strength, or proprioception training, targeting injury reduction rates according to risk exposure time in adolescent team sport contexts. Systematic review and meta-analysis. With established inclusion criteria, studies were searched in the following databases: Cochrane Central Register of Controlled Trials, MEDLINE, SPORTDiscus, Web of Science, EMBASE, CINAHL, and...
British Journal of Sports Medicine, 2015
This systematic review was conducted to evaluate the effect of Olympic weightlifting (OW) on vert... more This systematic review was conducted to evaluate the effect of Olympic weightlifting (OW) on vertical jump (VJ) height compared to a control condition, traditional resistance training and plyometric training. Five electronic databases were searched using terms related to OW and VJ. Studies needed to include at least one OW exercise, an intervention lasting ≥6 weeks; a comparison group of control, traditional resistance training or plyometric training; and to have measured VJ height. The methodological quality of studies was assessed using the Downs and Black Checklist. Random and fixed effects meta-analyses were performed to pool the results of the included studies and generate a weighted mean effect size (ES). Six studies (seven articles) were included in the meta-analyses and described a total of 232 participants (175 athletes and 57 physical education students) with resistance training experience, aged 19.5±2.2 years. Three studies compared OW versus control; four studies compared OW versus traditional resistance training; and three studies compared OW versus plyometric training. Meta-analyses indicated OW improved VJ height by 7.7% (95% CI 3.4 to 5.4 cm) compared to control (ES=0.62, p=0.03) and by 5.1% (95% CI 2.2 to 3.0 cm) compared to traditional resistance training (ES=0.64 p=0.00004). Change in VJ height was not different for OW versus plyometric training. OW is an effective training method to improve VJ height. The similar effects observed for OW and plyometric training on VJ height suggests that either of these methods would be beneficial when devising training programmes to improve VJ height.
The Journal of sports medicine and physical fitness
The purpose of this study was to examine whether a high--volume compared to a low--volume whole--... more The purpose of this study was to examine whether a high--volume compared to a low--volume whole--body resistance exercise session acutely impairs lung function. Fifteen competitive male bodybuilders (age 27.4 ± 5.4 y; body mass 89.7 ± 12.8 kg; stature 177.9 ± 4.8 cm), in a crossover trial, completed two resistance training protocols (high--volume: 5 sets per exercise; low--volume: 2 sets per exercise) and a control session (no exercise) on 3 separate occasions. The physiological demands of the two resistance exercise sessions were significantly different as indicated by greater VE, VO2, and HR (P<0.05), and lower PETCO2 (P<0.05) responses for the majority of exercises during the high--volume compared to low--volume session. No significant differences were found for lung function measures (FVC, SVC, FEV1, FEV3, FEV6, IC, ERV, and MVV) between pre-- and post--session for the low--volume and high-volume sessions. The findings suggest that the ventilatory muscle demands of a strenuous resistance exercise session are not great enough to acutely affect indices of lung function.
Strength and Conditioning Journal, 2015
Sports Medicine, 2015
Much of the existing research on the dietary intake of bodybuilders is dated and of limited quality.
Journal of Strength and Conditioning Research, 2013
Bodybuilding involves performing a series of poses on stage where the competitor is judged on aes... more Bodybuilding involves performing a series of poses on stage where the competitor is judged on aesthetic muscular appearance. The purpose of this study was to describe training practices and ergogenic aids used by competitive bodybuilders and to determine whether training practices comply with current recommendations for muscular hypertrophy. A web-based survey was completed by 127 competitive male bodybuilders. The results showed that during the off-season phase of training (OFF), the majority of respondents performed 3-6 sets per exercise (95.3%), 7-12 repetition maximum (RM) per set (77.0%), and 61- to 120-seconds recovery between sets and exercises (68.6%). However, training practices changed 6 weeks before competition (PRE), where there was an increased number of respondents who reported undertaking 3-4 sets per exercise at the expense of 5-6 sets per exercise (p < 0.001), an increase in the number reporting 10-15RM per set from 7-9RM per set (p < 0.001), and an increase in the number reporting 30-60 seconds vs. 61-180 seconds recovery between sets and exercises (p < 0.001). Anabolic steroid use was high among respondents competing in amateur competitions (56 of 73 respondents), whereas dietary supplementation was used by all respondents. The findings of this study demonstrate that competitive bodybuilders comply with current resistance exercise recommendations for muscular hypertrophy; however, these changed before competition during which there is a reduction resistance training volume and intensity. This alteration, in addition to an increase in aerobic exercise volume, is purportedly used to increase muscle definition. However, these practices may increase the risk of muscle mass loss in natural compared with amateur bodybuilders who reportedly use drugs known to preserve muscle mass.
Journal of Hepatology, 2012
Exercise is an integral component of lifestyle intervention aimed at weight loss, but an independ... more Exercise is an integral component of lifestyle intervention aimed at weight loss, but an independent benefit of exercise in NAFLD has also been suggested. We aimed to evaluate the efficacy of aerobic exercise and/or progressive resistance training for the modulation of liver fat and alanine aminotransferase (ALT) levels in adults. Relevant databases were searched up to August 2011 for controlled trials, which compared regular exercise vs. a non-exercise control on change in liver fat and/or ALT. Of the 16,822 studies from the initial search, 12 were included. There was a significant pooled effect size (ES) for the comparison between exercise therapy vs. control (ES=-0.37, 95% CI: -0.06 to -0.69; p=0.02), but only when interventions which compared combined exercise and diet vs. diet-alone and achieved substantial weight loss, were omitted. The benefit of exercise on liver fat occurred with minimal or no weight loss. There was no effect of exercise alone vs. control on ALT (ES=-0.15, 95% CI: 0.14 to -0.45; p=0.32). Individual reports of exercise interventions often have low sample sizes and insufficient power to detect clinically meaningful hepatic benefits. By pooling current research, we show clear evidence for a benefit of exercise therapy on liver fat but not ALT levels. This benefit is apparent with minimal or no weight loss and at exercise levels below current exercise recommendations for obesity management. Given the paucity of current treatment options, exercise provides a valid, low-cost therapy for disorders characterised by fatty liver.
Journal of the Peripheral Nervous System, 2015
Charcot-Marie-Tooth disease (CMT) is a slowly progressive hereditary degenerative disease and one... more Charcot-Marie-Tooth disease (CMT) is a slowly progressive hereditary degenerative disease and one of the most common neuromuscular disorders. Exercise may be beneficial to maintain strength and function for people with CMT, however, no comprehensive evaluation of the benefits and risks of exercise have been conducted. A systematic review was completed searching numerous electronic databases from earliest records to February 2015. Studies of any design including participants of any age with confirmed diagnosis of CMT that investigated the effects of exercise were eligible for inclusion. Of 13,301 articles identified following removal of duplicates, 11 articles including 9 unique studies met the criteria. Methodological quality of studies was moderate, sample sizes were small, and interventions and outcome measures used varied widely. Although the majority of the studies identified changes in one or more outcome measurements across exercise modalities, the majority were non-significant, possibly due to Type II errors. Significant effects described included improvements in strength, functional activities, and physiological adaptations following exercise. Despite many studies showing changes in strength and function following exercise, findings of this review should be met with caution due to the few studies available and moderate quality of evidence. Well-powered studies, harmonisation of outcome measures and clearly described interventions across studies would improve the quality and comparability of the evidence base. The optimal exercise modality and intensity for people with CMT as well as the long-term safety of exercise remain unclear.
Journal of sports science & medicine, 2012
This study investigated the effect of a high-volume compared to a low-volume resistance training ... more This study investigated the effect of a high-volume compared to a low-volume resistance training session on maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP). Twenty male subjects with resistance training experience (6.2 ± 3.2 y), in a crossover trial, completed two resistance training protocols (high-volume: 5 sets per exercise; low-volume: 2 sets per exercise) and a control session (no exercise) on 3 separate occasions. MIP and MEP decreased by 13.6% (p < 0.01) and 14.7% (p < 0.01) respectively from pre-session MIP and MEP, following the high-volume session. MIP and MEP were unaffected following the low-volume or the control sessions. MIP returned to pre-session values after 40 minutes, whereas MEP remained significantly reduced after 60 minutes post-session by 9.2% compared to pre-session (p < 0.01). The findings suggest that the high-volume session significantly decreased MIP and MEP post-session, implicating a substantially increased demand on th...
Journal of Strength and Conditioning Research, 2013
During resistance exercise, a brief Valsalva maneuver (VM) is unavoidable when lifting heavy load... more During resistance exercise, a brief Valsalva maneuver (VM) is unavoidable when lifting heavy loads (&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;80% of maximal voluntary contraction) or when lifting lighter loads to failure. It has been proposed that the performance of the VM during resistance exercise increases the stability of the spine because of augmented intra-abdominal pressure (IAP). However, resistance trainers are often advised to avoid the VM during resistance exercise because of potential adverse vascular events. The aim of this review was to establish the effect of the VM on IAP and to evaluate if the VM during resistance exercise is a safe practice. Relevant databases were searched to examine the effect of the VM on: (a) IAP and (b) hemodynamics during resistance exercise and reported adverse events. The data show that the VM alone increases IAP and that the VM augment IAP during various resistance exercises. An incremental rise in IAP was observed as the lifting intensity and effort increased, with IAP tending to be lower compared with peak IAP from the VM alone. The VM was associated with an increase in blood pressure during resistance exercise, but the VM alone was associated with greater hemodynamic changes. In conclusion, the VM effectively increases IAP, which may assist with spine stability and trunk rigidity during resistance exercise. The health risks associated with the VM during resistance exercise remain unconfirmed.
Journal of Sports Sciences, 2012
In this study, we examined the validity of a novel subjective scale for assessing resistance-exer... more In this study, we examined the validity of a novel subjective scale for assessing resistance-exercise effort. Seventeen male bodybuilders performed five sets of 10 repetitions at 70% of one-repetition maximum, for the bench press and squat. At the completion of each set, participants quantified their effort via the rating of perceived exertion (RPE) and novel estimatedrepetitions-to-failure scales, and continued repetitions to volitional exhaustion to determine actual-repetitions-to-failure. There were high correlations between estimated-and actual-repetitions-to-failure across sets for the bench press and squat (r 0.93; P 5 0.05). During sets 3, 4, and 5, estimated-repetitions-to-failure predicted the number of repetitions to failure for the bench press and squat, as indicated by smaller effect sizes for differences (ES ¼ 0.37-0.0). The estimated-repetitionsto-failure scale was reliable as indicated by high intraclass correlation coefficients (0.92) and narrow 95% limits of agreement (0.63 repetitions) for both the bench press and squat. Despite high correlations between RPE and actualrepetitions-to-failure (P 5 0.05), RPE at volitional fatigue was less than maximal for both exercises. Our results suggest that the estimated-repetitions-to-failure scale is valid for predicting onset of muscular failure, and can be used for the assessment and prescription of resistance exercise.
Journal of hepatology, 2015
Aerobic exercise reduces liver fat and visceral adipose tissue (VAT). However, there is limited d... more Aerobic exercise reduces liver fat and visceral adipose tissue (VAT). However, there is limited data from randomized trials to inform exercise programming recommendations. This study examined the efficacy of commonly prescribed exercise doses for reducing liver fat and VAT using a randomized placebo-controlled design. Inactive and overweight/obese adults received 8weeks of either; i) low to moderate intensity, high volume aerobic exercise (LO:HI, 50% VO2peak, 60min, 4d/week); ii) high intensity, low volume aerobic exercise (HI:LO, 70% VO2peak, 45min, 3d/week); iii) low to moderate intensity, low volume aerobic exercise (LO:LO, 50% VO2peak, 45min, 3d/week); or iv) placebo (PLA). Liver fat (spectroscopy) and VAT (magnetic resonance imaging) were measured before and after intervention. Forty-seven of the 48 (n=12 in each group) participants completed the trial. There were no serious adverse events. There was a significant change in group×time interaction in liver fat, which reduced in ...
Conference Presentations by Daniel Hackett
Introduction: Insulin resistance is a major part in the underlying pathology of type 2 diabetes (... more Introduction: Insulin resistance is a major part in the underlying pathology of type 2 diabetes (T2D) and has been independently associated with an increase risk of age-related chronic conditions including hypertension, CAD, stroke and cancer. Current exercise guidelines recommend that adults with T2D should undertake aerobic exercise 3 to 5 days per week, in combination with regular progressive resistance training to manage insulin resistance. Currently, there is limited data concerning the effect of regular exercise on dynamically measured insulin sensitivity in T2D.
Aim: The purpose of this study was to examine the effect of regular exercise training on insulin sensitivity in T2D using the collective data available from RCTs. In addition, we sought to determine whether short-term periods of inactivity diminish the exercise-induced improvement in insulin sensitivity.
Methods: Database searches were performed in AMED, MEDLINE, SPORTDiscus, CINAHL, EMBASE and Web of Science Core Collections. Eligible trials included exercise interventions that had ≥ 3 exercise sessions, and reported measurements of dynamic insulin sensitivity.
Results: 16 studies were eligible for review, and 14 were included for meta-analyses. Of the 14 studies, 9 studies reported the time of data collection from the last exercise bout for the time effect subgroup analyses. There was a significant pooled ES for the effect of exercise on insulin sensitivity (ES = -0.588; 95% CI: -0.816 to -0.359; P < 0.000). For the time effect sub analyses, a significant improvement in insulin sensitivity was in favour of exercise between 48 and 72 hours (ES = -0.702; 95% CI: -1.392 to -0.012; P = 0.046); and > 72 hours after the last exercise session (ES = -0.890; 95% CI: -1.675 to -0.105; P = 0.026).
Conclusion: This systematic review and meta-analyses found that regular exercise has a significant benefit on insulin sensitivity, and this effect may persist beyond 72 hours as a result of regular exercise training.
The American journal of sports medicine, Jan 16, 2015
Intensive sport participation in childhood and adolescence is an established cause of acute and o... more Intensive sport participation in childhood and adolescence is an established cause of acute and overuse injury. Interventions and programs designed to prevent such injuries are important in reducing individual and societal costs associated with treatment and recovery. Likewise, they help to maintain the accrual of positive outcomes from participation, such as cardiovascular health and skill development. To date, several studies have individually tested the effectiveness of injury prevention programs (IPPs). To determine the overall efficacy of structured multifaceted IPPs containing a combination of warm-up, neuromuscular strength, or proprioception training, targeting injury reduction rates according to risk exposure time in adolescent team sport contexts. Systematic review and meta-analysis. With established inclusion criteria, studies were searched in the following databases: Cochrane Central Register of Controlled Trials, MEDLINE, SPORTDiscus, Web of Science, EMBASE, CINAHL, and...
Sports medicine (Auckland, N.Z.), Jan 31, 2016
Muscle dysmorphia (MD) is associated with a self-perceived lack of size and muscularity, and is c... more Muscle dysmorphia (MD) is associated with a self-perceived lack of size and muscularity, and is characterized by a preoccupation with and pursuit of a hyper-mesomorphic body. MD symptoms may hypothetically be more prevalent in bodybuilders (BBs) than in non-bodybuilder resistance trainers (NBBRTs). Our objective was to compare MD symptomatology in BBs versus NBBRTs and identify psychological and other characteristics associated with MD in these groups. We searched relevant databases from earliest record to February 2015 for studies examining MD symptoms in BBs and/or NBBRTs. Included studies needed to assess MD using a psychometrically validated assessment tool. Study quality was evaluated using an adapted version of the validated Downs and Black tool. We calculated between-group standardized mean difference (effect sizes [ESs]) and 95 % confidence intervals (CIs) for each MD subscale, and performed meta-analysis when five or more studies used the same MD tool. We also extracted dat...
International journal of rehabilitation research. Internationale Zeitschrift fur Rehabilitationsforschung. Revue internationale de recherches de readaptation, Jan 12, 2016
This systematic review with a meta-analysis of studies was carried out to evaluate the potential ... more This systematic review with a meta-analysis of studies was carried out to evaluate the potential of overwork weakness on the basis of grip strength of dominant and nondominant hands in individuals with Charcot-Marie-Tooth disease (CMT). Numerous electronic databases were searched from the earliest records to February 2016. Studies of any design including participants older than 18 years of age with a confirmed diagnosis of CMT that measured grip strength of both hands using dynamometric testing were eligible for inclusion. Of 12 593 articles identified following removal of duplicates, five articles fulfilled the criteria. A total of 166 participants, mostly with CMT1 or CMT2, were described from the studies included. Hand and finger pinch grip strength for the dominant compared with the nondominant hand was not statistically different. There is no definitive evidence that preferential use of the dominant hand in CMT impairs function relative to the nondominant hand. Thus, robust exe...
Sports medicine (Auckland, N.Z.), Jan 18, 2016
Sports medicine (Auckland, N.Z.), Jan 14, 2015
It remains unclear whether repetitions leading to failure (failure training) or not leading to fa... more It remains unclear whether repetitions leading to failure (failure training) or not leading to failure (non-failure training) lead to superior muscular strength gains during resistance exercise. Failure training may provide the stimulus needed to enhance muscular strength development. However, it is argued that non-failure training leads to similar increases in muscular strength without the need for high levels of discomfort and physical effort, which are associated with failure training. We conducted a systematic review and meta-analysis to examine the effect of failure versus non-failure training on muscular strength. Five electronic databases were searched using terms related to failure and non-failure training. Studies were deemed eligible for inclusion if they met the following criteria: (1) randomised and non-randomised studies; (2) resistance training intervention where repetitions were performed to failure; (3) a non-failure comparison group; (4) resistance training interven...
The American journal of sports medicine, Jan 16, 2015
Intensive sport participation in childhood and adolescence is an established cause of acute and o... more Intensive sport participation in childhood and adolescence is an established cause of acute and overuse injury. Interventions and programs designed to prevent such injuries are important in reducing individual and societal costs associated with treatment and recovery. Likewise, they help to maintain the accrual of positive outcomes from participation, such as cardiovascular health and skill development. To date, several studies have individually tested the effectiveness of injury prevention programs (IPPs). To determine the overall efficacy of structured multifaceted IPPs containing a combination of warm-up, neuromuscular strength, or proprioception training, targeting injury reduction rates according to risk exposure time in adolescent team sport contexts. Systematic review and meta-analysis. With established inclusion criteria, studies were searched in the following databases: Cochrane Central Register of Controlled Trials, MEDLINE, SPORTDiscus, Web of Science, EMBASE, CINAHL, and...
British Journal of Sports Medicine, 2015
This systematic review was conducted to evaluate the effect of Olympic weightlifting (OW) on vert... more This systematic review was conducted to evaluate the effect of Olympic weightlifting (OW) on vertical jump (VJ) height compared to a control condition, traditional resistance training and plyometric training. Five electronic databases were searched using terms related to OW and VJ. Studies needed to include at least one OW exercise, an intervention lasting ≥6 weeks; a comparison group of control, traditional resistance training or plyometric training; and to have measured VJ height. The methodological quality of studies was assessed using the Downs and Black Checklist. Random and fixed effects meta-analyses were performed to pool the results of the included studies and generate a weighted mean effect size (ES). Six studies (seven articles) were included in the meta-analyses and described a total of 232 participants (175 athletes and 57 physical education students) with resistance training experience, aged 19.5±2.2 years. Three studies compared OW versus control; four studies compared OW versus traditional resistance training; and three studies compared OW versus plyometric training. Meta-analyses indicated OW improved VJ height by 7.7% (95% CI 3.4 to 5.4 cm) compared to control (ES=0.62, p=0.03) and by 5.1% (95% CI 2.2 to 3.0 cm) compared to traditional resistance training (ES=0.64 p=0.00004). Change in VJ height was not different for OW versus plyometric training. OW is an effective training method to improve VJ height. The similar effects observed for OW and plyometric training on VJ height suggests that either of these methods would be beneficial when devising training programmes to improve VJ height.
The Journal of sports medicine and physical fitness
The purpose of this study was to examine whether a high--volume compared to a low--volume whole--... more The purpose of this study was to examine whether a high--volume compared to a low--volume whole--body resistance exercise session acutely impairs lung function. Fifteen competitive male bodybuilders (age 27.4 ± 5.4 y; body mass 89.7 ± 12.8 kg; stature 177.9 ± 4.8 cm), in a crossover trial, completed two resistance training protocols (high--volume: 5 sets per exercise; low--volume: 2 sets per exercise) and a control session (no exercise) on 3 separate occasions. The physiological demands of the two resistance exercise sessions were significantly different as indicated by greater VE, VO2, and HR (P&amp;lt;0.05), and lower PETCO2 (P&amp;lt;0.05) responses for the majority of exercises during the high--volume compared to low--volume session. No significant differences were found for lung function measures (FVC, SVC, FEV1, FEV3, FEV6, IC, ERV, and MVV) between pre-- and post--session for the low--volume and high-volume sessions. The findings suggest that the ventilatory muscle demands of a strenuous resistance exercise session are not great enough to acutely affect indices of lung function.
Strength and Conditioning Journal, 2015
Sports Medicine, 2015
Much of the existing research on the dietary intake of bodybuilders is dated and of limited quality.
Journal of Strength and Conditioning Research, 2013
Bodybuilding involves performing a series of poses on stage where the competitor is judged on aes... more Bodybuilding involves performing a series of poses on stage where the competitor is judged on aesthetic muscular appearance. The purpose of this study was to describe training practices and ergogenic aids used by competitive bodybuilders and to determine whether training practices comply with current recommendations for muscular hypertrophy. A web-based survey was completed by 127 competitive male bodybuilders. The results showed that during the off-season phase of training (OFF), the majority of respondents performed 3-6 sets per exercise (95.3%), 7-12 repetition maximum (RM) per set (77.0%), and 61- to 120-seconds recovery between sets and exercises (68.6%). However, training practices changed 6 weeks before competition (PRE), where there was an increased number of respondents who reported undertaking 3-4 sets per exercise at the expense of 5-6 sets per exercise (p &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.001), an increase in the number reporting 10-15RM per set from 7-9RM per set (p &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.001), and an increase in the number reporting 30-60 seconds vs. 61-180 seconds recovery between sets and exercises (p &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.001). Anabolic steroid use was high among respondents competing in amateur competitions (56 of 73 respondents), whereas dietary supplementation was used by all respondents. The findings of this study demonstrate that competitive bodybuilders comply with current resistance exercise recommendations for muscular hypertrophy; however, these changed before competition during which there is a reduction resistance training volume and intensity. This alteration, in addition to an increase in aerobic exercise volume, is purportedly used to increase muscle definition. However, these practices may increase the risk of muscle mass loss in natural compared with amateur bodybuilders who reportedly use drugs known to preserve muscle mass.
Journal of Hepatology, 2012
Exercise is an integral component of lifestyle intervention aimed at weight loss, but an independ... more Exercise is an integral component of lifestyle intervention aimed at weight loss, but an independent benefit of exercise in NAFLD has also been suggested. We aimed to evaluate the efficacy of aerobic exercise and/or progressive resistance training for the modulation of liver fat and alanine aminotransferase (ALT) levels in adults. Relevant databases were searched up to August 2011 for controlled trials, which compared regular exercise vs. a non-exercise control on change in liver fat and/or ALT. Of the 16,822 studies from the initial search, 12 were included. There was a significant pooled effect size (ES) for the comparison between exercise therapy vs. control (ES=-0.37, 95% CI: -0.06 to -0.69; p=0.02), but only when interventions which compared combined exercise and diet vs. diet-alone and achieved substantial weight loss, were omitted. The benefit of exercise on liver fat occurred with minimal or no weight loss. There was no effect of exercise alone vs. control on ALT (ES=-0.15, 95% CI: 0.14 to -0.45; p=0.32). Individual reports of exercise interventions often have low sample sizes and insufficient power to detect clinically meaningful hepatic benefits. By pooling current research, we show clear evidence for a benefit of exercise therapy on liver fat but not ALT levels. This benefit is apparent with minimal or no weight loss and at exercise levels below current exercise recommendations for obesity management. Given the paucity of current treatment options, exercise provides a valid, low-cost therapy for disorders characterised by fatty liver.
Journal of the Peripheral Nervous System, 2015
Charcot-Marie-Tooth disease (CMT) is a slowly progressive hereditary degenerative disease and one... more Charcot-Marie-Tooth disease (CMT) is a slowly progressive hereditary degenerative disease and one of the most common neuromuscular disorders. Exercise may be beneficial to maintain strength and function for people with CMT, however, no comprehensive evaluation of the benefits and risks of exercise have been conducted. A systematic review was completed searching numerous electronic databases from earliest records to February 2015. Studies of any design including participants of any age with confirmed diagnosis of CMT that investigated the effects of exercise were eligible for inclusion. Of 13,301 articles identified following removal of duplicates, 11 articles including 9 unique studies met the criteria. Methodological quality of studies was moderate, sample sizes were small, and interventions and outcome measures used varied widely. Although the majority of the studies identified changes in one or more outcome measurements across exercise modalities, the majority were non-significant, possibly due to Type II errors. Significant effects described included improvements in strength, functional activities, and physiological adaptations following exercise. Despite many studies showing changes in strength and function following exercise, findings of this review should be met with caution due to the few studies available and moderate quality of evidence. Well-powered studies, harmonisation of outcome measures and clearly described interventions across studies would improve the quality and comparability of the evidence base. The optimal exercise modality and intensity for people with CMT as well as the long-term safety of exercise remain unclear.
Journal of sports science & medicine, 2012
This study investigated the effect of a high-volume compared to a low-volume resistance training ... more This study investigated the effect of a high-volume compared to a low-volume resistance training session on maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP). Twenty male subjects with resistance training experience (6.2 ± 3.2 y), in a crossover trial, completed two resistance training protocols (high-volume: 5 sets per exercise; low-volume: 2 sets per exercise) and a control session (no exercise) on 3 separate occasions. MIP and MEP decreased by 13.6% (p < 0.01) and 14.7% (p < 0.01) respectively from pre-session MIP and MEP, following the high-volume session. MIP and MEP were unaffected following the low-volume or the control sessions. MIP returned to pre-session values after 40 minutes, whereas MEP remained significantly reduced after 60 minutes post-session by 9.2% compared to pre-session (p < 0.01). The findings suggest that the high-volume session significantly decreased MIP and MEP post-session, implicating a substantially increased demand on th...
Journal of Strength and Conditioning Research, 2013
During resistance exercise, a brief Valsalva maneuver (VM) is unavoidable when lifting heavy load... more During resistance exercise, a brief Valsalva maneuver (VM) is unavoidable when lifting heavy loads (&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;80% of maximal voluntary contraction) or when lifting lighter loads to failure. It has been proposed that the performance of the VM during resistance exercise increases the stability of the spine because of augmented intra-abdominal pressure (IAP). However, resistance trainers are often advised to avoid the VM during resistance exercise because of potential adverse vascular events. The aim of this review was to establish the effect of the VM on IAP and to evaluate if the VM during resistance exercise is a safe practice. Relevant databases were searched to examine the effect of the VM on: (a) IAP and (b) hemodynamics during resistance exercise and reported adverse events. The data show that the VM alone increases IAP and that the VM augment IAP during various resistance exercises. An incremental rise in IAP was observed as the lifting intensity and effort increased, with IAP tending to be lower compared with peak IAP from the VM alone. The VM was associated with an increase in blood pressure during resistance exercise, but the VM alone was associated with greater hemodynamic changes. In conclusion, the VM effectively increases IAP, which may assist with spine stability and trunk rigidity during resistance exercise. The health risks associated with the VM during resistance exercise remain unconfirmed.
Journal of Sports Sciences, 2012
In this study, we examined the validity of a novel subjective scale for assessing resistance-exer... more In this study, we examined the validity of a novel subjective scale for assessing resistance-exercise effort. Seventeen male bodybuilders performed five sets of 10 repetitions at 70% of one-repetition maximum, for the bench press and squat. At the completion of each set, participants quantified their effort via the rating of perceived exertion (RPE) and novel estimatedrepetitions-to-failure scales, and continued repetitions to volitional exhaustion to determine actual-repetitions-to-failure. There were high correlations between estimated-and actual-repetitions-to-failure across sets for the bench press and squat (r 0.93; P 5 0.05). During sets 3, 4, and 5, estimated-repetitions-to-failure predicted the number of repetitions to failure for the bench press and squat, as indicated by smaller effect sizes for differences (ES ¼ 0.37-0.0). The estimated-repetitionsto-failure scale was reliable as indicated by high intraclass correlation coefficients (0.92) and narrow 95% limits of agreement (0.63 repetitions) for both the bench press and squat. Despite high correlations between RPE and actualrepetitions-to-failure (P 5 0.05), RPE at volitional fatigue was less than maximal for both exercises. Our results suggest that the estimated-repetitions-to-failure scale is valid for predicting onset of muscular failure, and can be used for the assessment and prescription of resistance exercise.
Journal of hepatology, 2015
Aerobic exercise reduces liver fat and visceral adipose tissue (VAT). However, there is limited d... more Aerobic exercise reduces liver fat and visceral adipose tissue (VAT). However, there is limited data from randomized trials to inform exercise programming recommendations. This study examined the efficacy of commonly prescribed exercise doses for reducing liver fat and VAT using a randomized placebo-controlled design. Inactive and overweight/obese adults received 8weeks of either; i) low to moderate intensity, high volume aerobic exercise (LO:HI, 50% VO2peak, 60min, 4d/week); ii) high intensity, low volume aerobic exercise (HI:LO, 70% VO2peak, 45min, 3d/week); iii) low to moderate intensity, low volume aerobic exercise (LO:LO, 50% VO2peak, 45min, 3d/week); or iv) placebo (PLA). Liver fat (spectroscopy) and VAT (magnetic resonance imaging) were measured before and after intervention. Forty-seven of the 48 (n=12 in each group) participants completed the trial. There were no serious adverse events. There was a significant change in group×time interaction in liver fat, which reduced in ...
Introduction: Insulin resistance is a major part in the underlying pathology of type 2 diabetes (... more Introduction: Insulin resistance is a major part in the underlying pathology of type 2 diabetes (T2D) and has been independently associated with an increase risk of age-related chronic conditions including hypertension, CAD, stroke and cancer. Current exercise guidelines recommend that adults with T2D should undertake aerobic exercise 3 to 5 days per week, in combination with regular progressive resistance training to manage insulin resistance. Currently, there is limited data concerning the effect of regular exercise on dynamically measured insulin sensitivity in T2D.
Aim: The purpose of this study was to examine the effect of regular exercise training on insulin sensitivity in T2D using the collective data available from RCTs. In addition, we sought to determine whether short-term periods of inactivity diminish the exercise-induced improvement in insulin sensitivity.
Methods: Database searches were performed in AMED, MEDLINE, SPORTDiscus, CINAHL, EMBASE and Web of Science Core Collections. Eligible trials included exercise interventions that had ≥ 3 exercise sessions, and reported measurements of dynamic insulin sensitivity.
Results: 16 studies were eligible for review, and 14 were included for meta-analyses. Of the 14 studies, 9 studies reported the time of data collection from the last exercise bout for the time effect subgroup analyses. There was a significant pooled ES for the effect of exercise on insulin sensitivity (ES = -0.588; 95% CI: -0.816 to -0.359; P < 0.000). For the time effect sub analyses, a significant improvement in insulin sensitivity was in favour of exercise between 48 and 72 hours (ES = -0.702; 95% CI: -1.392 to -0.012; P = 0.046); and > 72 hours after the last exercise session (ES = -0.890; 95% CI: -1.675 to -0.105; P = 0.026).
Conclusion: This systematic review and meta-analyses found that regular exercise has a significant benefit on insulin sensitivity, and this effect may persist beyond 72 hours as a result of regular exercise training.