George Nassis - Academia.edu (original) (raw)

Papers by George Nassis

Epidemiology, Biostatistics, and Public Health

Background: in the Greek population, the association between obesity and Health-Related Quality o... more Background: in the Greek population, the association between obesity and Health-Related Quality of Life (HRQoL) has not been examined so far. Thus, the purpose of the present study is to explore obesity-related predictors of HRQoL in a sample of Greek healthy adults. Methods: a cross-sectional design was used. The sample consisted of three hundred twenty seven healthy men (N=105) and women (N=222), between the ages of 30 and 50 years (mean age=39.57 ± 6.68) who lived in Athens. Body mass index (BMI), waist to hip ratio (WHR), and body fat (BF) were assessed. HRQoL was evaluated using the short-form 36 (SF-36) health survey, which consists of eight subscales and two health factors (physical and psychological health). Socio-demographic variables and health-related behaviours were assessed by questionnaires. Separate hierarchical regression analyses were conducted to examine the associations between BMI, WHR, BF and SF-36 health survey subscales and factors. Results: socio-demographic ...

Journal of Sports Science and Medicine, 2021

We investigated whether single or combined methods of pre-cooling could affect high-intensity exe... more We investigated whether single or combined methods of pre-cooling could affect high-intensity exercise performance in a hot environment. Seven male athletes were subjected to four experimental conditions for 30 min in a randomised order. The four experimental conditions were: 1) wearing a vest cooled to a temperature of 4 ℃ (Vest), 2) consuming a beverage cooled to a temperature of 4 ℃ (Beverage), 3) simultaneous usage of vest and consumption of beverage (Mix), and 4) the control trial without pre-cooling (CON). Following those experimental conditions, they exercised at a speed of 80% VO2max until exhaustion in the heat (38.1 ± 0.6 ℃, 55.3 ± 0.3% RH). Heart rate (HR), rectal temperature (Tcore), skin temperature (Tskin), sweat loss (SL), urine specific gravity (USG), levels of sodium (Na+) and potassium (K+), rating of perceived exertion (RPE), thermal sensation (TS), and levels of blood lactic acid ([Bla]) were monitored. Performance was improved using the mixed pre-cooling strateg...

Kinesiology, 2021

The purpose of the present study was to examine the effect of different conditioning activities (... more The purpose of the present study was to examine the effect of different conditioning activities (CAs) on short-term increase in sprint performance. In twelve male sprinters (21.1±2.6 years, 100 m performance: 11.5±0.6 s) their body composition, half squat maximum strength, 100 m sprinting and countermovement jump performances were evaluated. The performance of a 50 m sprint (splits at 10 m, 30 m and 50 m) was evaluated before and 5, 10 and 15 min after four postactivation performance enhancement CAs on different occasions: [1] 3 sets x 4 s maximum isometric half squat (IHF), [2] 3 sets x 3 consecutive countermovement jumps (cCMJs), [3] 3 repetitions x 30 m overspeed sprinting (OVSP) and [4] dynamic submaximal half squat (2 sets x 2 reps x 90% of 1-RM half squat; HSQ). Significant improvements of sprinting performance were found 10 and 15 min following the cCMJs, OVSP and HSQ’s interventions, in all distances (p<.05; -2.14±1.21% and -3.56±2.47%), without any significant difference...

British Journal of Sports Medicine, 2020

China is experiencing significant public health challenges related to social and demographic tran... more China is experiencing significant public health challenges related to social and demographic transitions and lifestyle transformations following unprecedented economic reforms four decades ago. Of particular public health concern is the fourfold increase in overweight and obesity rates in the nation’s youth population, coupled with the low prevalence of adolescents meeting recommended levels of physical activity. Improving the overall health of China’s more than 170 million children and adolescents has become a national priority. However, advancing nationwide health initiatives and physical activity promotion in this population has been hampered by the lack of a population-specific and culturally relevant consensus on recommendations for achieving these ends. To address this deficiency and inform policies to achieve Healthy China 2030 goals, a panel of Chinese experts, complemented by international professionals, developed this consensus statement. The consensus was achieved through...

International Journal of Environmental Research and Public Health, 2020

We aimed to evaluate the effects of the COVID-19 lock down on lifestyle in China during the initi... more We aimed to evaluate the effects of the COVID-19 lock down on lifestyle in China during the initial stage of the pandemic. A questionnaire was distributed to Chinese adults living in 31 provinces of China via the internet using a snowball sampling strategy. Information on 7-day physical activity recall, screen time, and emotional state were collected between January 24 and February 2, 2020. ANOVA, χ² test, and Spearman’s correlation coefficients were used for statistical analysis. 12,107 participants aged 18–80 years were included. During the initial phase of the COVID-19 outbreak, nearly 60% of Chinese adults had inadequate physical activity (95% CI 56.6%–58.3%), which was more than twice the global prevalence (27.5%, 25.0%–32.2%). Their mean screen time was more than 4 hours per day while staying at home (261.3 ± 189.8 min per day), and the longest screen time was found in young adults (305.6 ± 217.5 min per day). We found a positive and significant correlation between provincial ...

Sports Medicine - Open, 2019

Scandinavian Journal of Medicine & Science in Sports, 2018

BMJ Open Sport & Exercise Medicine, 2019

BackgroundSleep quality is an essential component of athlete’s recovery. However, a better unders... more BackgroundSleep quality is an essential component of athlete’s recovery. However, a better understanding of the parameters to adequately quantify sleep quality in team sport athletes is clearly warranted.ObjectiveTo identify which parameters to use for sleep quality monitoring in team sport athletes.MethodsSystematic searches for articles reporting the qualitative markers related to sleep in team sport athletes were conducted in PubMed, Scopus, SPORTDiscus and Web of Science online databases. The systematic review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. For the meta-analysis, effect sizes with 95% CI were calculated and heterogeneity was assessed using a random-effects model. The coefficient of variation (CV) with 95% CI was also calculated to assess the level of instability of each parameter.ResultsIn general, 30 measuring instruments were used for monitoring sleep quality. A meta-analysis was undertaken on 15 of these parameters....

Journal of sports sciences, Jan 19, 2015

The purpose of this study was to investigate the responses of salivary hormones and salivary secr... more The purpose of this study was to investigate the responses of salivary hormones and salivary secretory immunoglobulin A (SIgA) and anxiety in winners and losers during an international judo competition. Twenty-three trained, male, national-level judo athletes provided three saliva samples during a competition day: morning, in anticipation of competition after an overnight fast, mid-competition, and post-competition within 15 min post-fight for determination of salivary cortisol, salivary testosterone, salivary testosterone/cortisol ratio, SIgA absolute concentrations, SIgA secretion rate and saliva flow rate. The competitive state anxiety inventory questionnaire was completed by the athletes (n = 12) after the first saliva collection for determination of somatic anxiety, cognitive anxiety and self-confidence. Winners were considered 1-3 ranking place (n = 12) and losers (n = 11) below third place in each weight category. Winners presented higher anticipatory salivary cortisol concen...

Applied Physiology, Nutrition, and Metabolism, 2015

This study examined the effects of postexercise chocolate milk (CM) or water (W) consumption duri... more This study examined the effects of postexercise chocolate milk (CM) or water (W) consumption during 5 days of intensive judo training with concomitant weight loss on salivary cortisol and testosterone, salivary secretory immunoglobulin A (SIgA), delayed-onset muscle soreness (DOMS), and judo-related performance. Twelve trained male judo athletes engaged in 5 days of intensive judo training followed by a simulated judo competition, on 2 separate training weeks 14 days apart. The athletes consumed 1000 mL of W (week 1) or CM (week 2) immediately post-training. During both weeks, athletes were instructed to “make weight” for the upcoming competition. Performance in timed push-ups and the Special Judo Fitness Test improved by 14.6% and 6.8%, respectively, at the end of the training week with CM consumption (both p < 0.001). Decreased salivary cortisol (p < 0.01) and a trend for an increased salivary testosterone/cortisol ratio (p = 0.07) were also observed midweek in the CM condit...

Sports medicine (Auckland, N.Z.), Jan 23, 2015

Exercising in the heat induces thermoregulatory and other physiological strain that can lead to i... more Exercising in the heat induces thermoregulatory and other physiological strain that can lead to impairments in endurance exercise capacity. The purpose of this consensus statement is to provide up-to-date recommendations to optimize performance during sporting activities undertaken in hot ambient conditions. The most important intervention one can adopt to reduce physiological strain and optimize performance is to heat acclimatize. Heat acclimatization should comprise repeated exercise-heat exposures over 1-2 weeks. In addition, athletes should initiate competition and training in an euhydrated state and minimize dehydration during exercise. Following the development of commercial cooling systems (e.g., cooling vests), athletes can implement cooling strategies to facilitate heat loss or increase heat storage capacity before training or competing in the heat. Moreover, event organizers should plan for large shaded areas, along with cooling and rehydration facilities, and schedule eve...

International Journal of Obesity, 2007

Sports Medicine - Open, 2015

The Journal of sports medicine and physical fitness, 2012

The purpose of this study was to examine the effects of cardiorespiratory fitness (CRF) and obesi... more The purpose of this study was to examine the effects of cardiorespiratory fitness (CRF) and obesity on arterial blood pressure and its determinants at rest and during isometric handgrip exercise (IHG) in children. Fourty-eight healthy children aged 11.6±0.3 (mean ±SE) years, (24 obese or overweight [OB/OV]; 24 normal weight [NO]) participated in the study. Both groups were divided into fit or unfit subgroups according to children's performance of an exercise test (PWC170). Arterial pressure and its determinants were recorded with the use of a photoplethysmographic device (FINOMETER) during 5 minutes of rest and 3 minutes of IHG at 30% of maximum voluntary contraction. At rest and during IHG, unfit OB/OV children had higher systolic, mean arterial pressure, and rate pressure product (P≤0.05) than fit OB/OV children whose responses were similar to NO children, fit or unfit. Changes from rest, in cardiac output, cardiac index, and stroke volume were higher in unfit than in fit OB/O...

Journal of sports science & medicine, 2013

Dietary supplement (DS) intake is high in elite level athletes, however few studies have investig... more Dietary supplement (DS) intake is high in elite level athletes, however few studies have investigated the impact that the performance level of the athletes has on supplementation intake in individual and team sports. The purpose of the study was to determine and compare the DS intake among individual and team sport athletes of various performance levels. A total of 2845 participants (athletes: 2783, controls: 62) between the ages of 11 and 44 years old participated in the study. A 3-page questionnaire was developed to assess the intake of DS. Athletes were categorized based on participation in individual (n = 775) and team sports (n = 2008). To assess the effect of performance level in supplementation intake, athletes were categorized based on training volume, participation in the national team, and winning at least one medal in provincial, national, international or Olympic games. Overall, 37% of all athletes of various performance levels reported taking at least one DS in the last...

Journal of sports science & medicine, 2008

The purpose of this study was to examine the role of active muscle mass on cardiovascular drift (... more The purpose of this study was to examine the role of active muscle mass on cardiovascular drift (CVdrift) during prolonged exercise. Twelve subjects with peak oxygen uptake (VO2peak) of 3.52 ± 0.52 L·min(-1) (mean ± SD) cycled for 55 min with 80 revolutions per minute with either two legs (2-legged) or one leg (1-legged). Oxygen uptake was at 60% of VO2peak throughout the 2-legged trial and at half of this value in 1- legged condition. Cardiac output (CO-CO2 rebreathing), heart rate (HR) and quadriceps integrated electromyographic activity (iEMG) were higher (p < 0.01) during 2-legged than 1- legged exercise. Changes in stroke volume from 20 to 50 min of exercise were greater in 2-legged than in 1-legged (∆SV: -20.8 ± 0.8 vs. -13.3 ± 1.3 ml·beat(-1), p < 0.05). Similarly, changes in heart rate (∆HR) were +18.5 ± 0.8 and +10.7 ± 1.0 beats·min(-1), in 2-legged and 1-legged, respectively (p < 0.01). Calculated blood volume changes declined significantly in 2-legged exercise (∆...

Journal of the Human-Environment System, 2002