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Papers by Boram Lim

Medicine & Science in Sports & Exercise

Running economy (RE; ml·kg-1·km1) considers as a valid predictor of endurance running performance... more Running economy (RE; ml·kg-1·km1) considers as a valid predictor of endurance running performance. Theoretically, improving RE allows runners to cover more distance at constant speed or run faster at a given distance. Stride frequency (SF) is one of the important parameters that affects running performance. The purpose of this study was to investigate the effect of SF on RE and distance while running on the treadmill at the speed of V̇O2max (sV̇O2max) until volitional fatigue. The second purpose was to determine a relationship between RE and running distance during high intensity running. We hypothesized that both RE and running distance would affect significantly by SF variations and there is a positive relationship between RE and running distance. Ten male recreational runners (age: 25.8 ± 5.0 yrs, height: 171.4 ± 6.2 cm, mass: 71.9 ± 7.5 kg) completed total seven experimental sessions including graded exercise test and running session for determining V̇O2max (55.4 ± 5.9 ml·kg-1·m...

Journal of Health, Sports, and Kinesiology

Medicine & Science in Sports & Exercise

Tiago M. Barbosa, Jia Wen Yam, Govindasamy Balasekaran, FACSM, Daniel A. Marinho. Polytechnic Ins... more Tiago M. Barbosa, Jia Wen Yam, Govindasamy Balasekaran, FACSM, Daniel A. Marinho. Polytechnic Institute of Bragança, Bragança, Portugal; Research Centre in Sports, Health and Human Development, Vila Real, Portugal; Nanyang Technological University, Singapore, Singapore. Nanyang Technological University, Singapore, Singapore. Research Centre in Sports, Health and Human Development, Vila Real, Portugal; University of Beira Interior, Covilhã, Portugal.

Medicine & Science in Sports & Exercise

RESULTS: There were no statistical differences between Control (2.9±1.4 a.u.), RPR (2.9±1.6 a.u.)... more RESULTS: There were no statistical differences between Control (2.9±1.4 a.u.), RPR (2.9±1.6 a.u.), or GA (3.2±1.7 a.u.) for the feeling scale (p=0.80). There were no statistical differences between Control (2.01±0.03 s), RPR (2.02±0.07 s), or GA (1.93±0.31 s) for sprint time (p=0.48). Total muscular contribution was not statistically different (condition main effect: p=0.90) during Control (quadriceps: 70±12%, gluteui maximi: 16±8%, hamstrings: 14±9%), RPR (quadriceps: 61±11%, gluteui maximi: 17±5%, hamstrings: 22±8%), or GA (quadriceps: 65±11%, gluteui maximi: 17±5%, hamstrings: 18±8%). CONCLUSION: These data indicate no alterations in muscular excitation following RPR or GA during short sprints in healthy males. Furthermore, RPR or GA did not enhance whole-body feeling or performance.

Medicine & Science in Sports & Exercise

During the swimming portion of a triathlon, athletes can use a wetsuit if water temperature is be... more During the swimming portion of a triathlon, athletes can use a wetsuit if water temperature is below a threshold value. There are two general categories of wetsuits: Full sleeve (FSW) and sleeveless (SLW). It is not known if the type of wetsuit worn influences muscle activity patterns. PURPOSE: Compare shoulder muscle activity patterns while wearing different wetsuit designs. METHODS: Subjects (n=7; 45.7±8.0 yrs, 174.8±10.5 cm, 70.1±9.4 kg) completed three swim conditions on the same day: no wetsuit (NWS), FSW, or SLW. Rest was provided between conditions as needed. Muscle activity (posterior deltoid (PD), anterior deltoid (AD)) was measured (2000 Hz) using a water proofed electromyography (EMG) system (Cometa). After a selfdirected warm-up, subjects swam a length of the pool at a ‘somewhat hard’ pace (25 m or 50 m depending on pool set up). EMG data were processed by removing any zero offset, calculating the absolute value, and smoothing (low-pass, cutoff frequency = 4 Hz). PD smoothed data were used to identify the beginning and ending points of five consecutive stroke cycles with extracted data time normalized. Pearson correlation coefficients (r) were calculated between NWS-FSW, NWS-SLW, and FSW-SLW for each extracted pattern data set per muscle with each r transformed to a Z-score. Z-scores and r were each compared between conditions using a 1 x 3 (wetsuit condition) repeated measures ANOVA (α=0.05). RESULTS: Neither r nor Z-score for either muscle was influenced by wetsuit condition (p>0.05). PD EMG patterns were moderately correlated between conditions (NWS-FSW NWS-SLW FSW-SLW: r=0.66±0.16, 0.65±0.16, 0.62±0.20) whereas strength of AD correlations were weak (r=0.37±0.33, 0.42±0.19, 0.39±0.21). CONCLUSION: Muscle activity patterns of PD were more strongly similar than AD between swimming without a wetsuit then with a wetsuit as well as between wetsuit conditions. The weaker AD correlations between conditions may be influenced by horizontal position due to buoyancy force and/or possible resistance to shoulder movements of the wetsuit.

Medicine & Science in Sports & Exercise

Swim-related fatalities have raised safety concerns in the sport of triathlon. As a majority of d... more Swim-related fatalities have raised safety concerns in the sport of triathlon. As a majority of deaths occur during the swim, there are strict guidelines related to water temperatures and the use of wetsuits in triathlon events governed by USA Triathlon (USAT). Due to the varying water temperatures, athletes can select from a wide variety of wetsuit models. Two main categories of wetsuit models are sleeveless and full sleeve. The use of a wetsuit in warm water may increase body heat storage and may result in an increase in core temperature. However, there are no data investigating the influence of triathlon wetsuit design on core temperature when swimming in warm water. PURPOSE: The purpose of this study was to examine the influence of wetsuit design on core temperature responses during swimming in warm water (25.5 °C). METHODS: Three experienced triathletes (mean ± standard deviation (SD), age 48 ± 4.93 years, height 1.73 ± 0.09 m, weight 71.62 ± 8.54 kg) participated in the study. At least 8 hours prior to attending the test session, participants swallowed an ingestible core temperature pill. Before beginning the test session, core temperature (Tc) data were transferred to the monitor and sample rate was set to 0.1 Hz (1 sample every 10 s). Testing consisted of a self-directed warm-up followed by a 500-m swim in an indoor pool (set to either 25-m or 50-m in length) for each condition: no wetsuit (NW), sleeveless wetsuit (SL), and full sleeve wetsuit (FS). Participants swam at a self-selected pace at a somewhat hard intensity (Borg Rating of Perceived Exertion = 13). Participants were required to rest until core temperature was within 0.5 °C of baseline before beginning the next condition. Core temperature data were transferred to the monitor after each swim. Average Tc during the first and last minute of each swim was computed for analysis. A 2 (time) x 3 (wetsuit condition) repeated measures ANOVA was used (α;=0.05). RESULTS: Tc was not influenced by the interaction of time and wetsuit (p>0.05) and there was no main effect for time (p>0.05) nor wetsuit condition (p>0.05). Mean values for Tc between NW, SL, and FS were 37.82 ± 0.44 °C, 37.64 ± 0.68 °C, and 37.64 ± 0.42 °C, respectively. CONCLUSIONS: These pilot results indicate that wetsuit design does not significantly influence thermoregulatory responses.

Medicine & Science in Sports & Exercise

In a triathlon event, people use various strategies and equipment for enhancing their triathlon p... more In a triathlon event, people use various strategies and equipment for enhancing their triathlon performance in each exercise mode (i.e., swim, bike, run). During the swimming portion of a race, triathletes will typically wear a wetsuit that is categorized as either full sleeve or sleeveless. Anecdotally, triathletes may select a sleeveless wetsuit because the full sleeve may increase shoulder movement resistance. PURPOSE: The purpose of this study was to investigate shoulder muscle activity influenced by wetsuit design. METHODS: Seven subjects (5 male and 2 female, age: 45.7 ± 8.0 yrs, height: 174.8 ± 10.5cm, mass: 70.1 ± 9.4 kg) participated in the experiment. Muscle activity of the Anterior Deltoid (AD) and Posterior Deltoid (PD) was measured (2000 Hz) using a water proofed electromyography (EMG) system (MiniWave, Cometa, Italy). After a self-directed warm-up, participants were asked to swim 50m at a ‘somewhat hard’ pace that they could maintain the pace for a sprint triathlon distance (750m) for each condition: No wetsuit (NWS), sleeveless wetsuit (SLW), and full sleeve (FSW). PD EMG data were smoothed using a 4 order Butterworth filter (cutoff frequency = 4 Hz). The smoothed data were used to identify the beginning and ending points of a stroke cycle. Five consecutive stroke cycles were then extracted for analysis as well as the time to complete the five cycles. Data analysis was performed using the raw unfiltered EMG data which were reduced by removing any zero offset, full wave rectifying the signal, and calculating the average EMG across the 5 stroke cycles (PDavg, ADavg). Time and average data were compared between conditions using a 1 x 3 (wetsuit condition) repeated measures ANOVA. RESULTS: Muscle activity of both AD and PD were not different among all wetsuit conditions (p>0.05). However, time was different among conditions (p<0.05) with FSW being shorter than NWS (p<0.05), but between the two wetsuits (FSW and SLW) were not different (p>0.05). CONCLUSION: While swimming at a somewhat hard intensity, wetsuit design did not influence muscle activity of the shoulder muscle. However, stroke time was influenced by wearing a wetsuit regardless of design. Triathletes might get a benefit to reduce their swimming race time by wearing a wetsuit regardless of full-sleeve or sleeveless.

Medicine & Science in Sports & Exercise

Running economy(RE) is considered to be a critical factor to improve running performance. Stride ... more Running economy(RE) is considered to be a critical factor to improve running performance. Stride frequency(SF) is an important variable for determining RE. The importance of SF has gained more attention in recent years, especially for recreational runners. However, no previous research has investigated the interaction between running performance and SF at the velocity of VO2max. PURPOSE: To investigate the effect of five different SF variations on running performance until volitional fatigue at the velocity of VO2max. METHODS: Fourteen male recreational runners (Age = 25.8 ± 4.96 years, Height = 171 ± 6.2cm, Body Mass = 71.9 ± 7.5kg) measured VO2max (54 ± 5.6 ml/kg/min) and preferred stride frequency (PSF; 89.3 ± 4 / min) through a graded exercise test (GXT) and running session, respectively. Running speed was determined based on each individual's VO2max via the metabolic equation for gross VO2 in metric units by ACSM. Participants ran on the treadmill (0% grade) with five SF conditions (PSF, ±5%, ±10%) until time to exhaustion. Data were analyzed using a one way ANOVA with repeated measures and Tukey HSD post hoc. RESULTS: The total running performance (time, distance), energy expenditures (kcal), and oxygen consumption (VO2) were statistically significant among SF variations (p<0.05). Additionally, the respiratory exchange ratio iii (RER), respiratory rate (RR), and ventilation (VE) were no statistically significant (p>0.05). CONCLUSION: The SF variations have a significant influence on running performance. The relationship between SF variations and other variables (RER, RR, VE) were possibly related to the central governor theory to delay the onset of fatigue. These results suggest that recreational runners could use a 105% of PSF to improve running performance with the better RE.

Journal of Health, Sports, and Kinesiology, 2021

Given the nature of a triathlon race, the cycling distance is typically much longer than swimming... more Given the nature of a triathlon race, the cycling distance is typically much longer than swimming and running across race distances from sprint to Ironman. Besides, triathletes should try to not only maintain a certain level of cycling power but also consider cycling economy to make a better performance in both the cycling portion and the overall race (Bonacci et al., 2013; Sleivert & Rowland, 1996; Swinnen et al., 2018). The cycling economy is an important indicator to predict cycling performance in terms of time to complete a certain distance. Both cycling economy and performance are determined by the interaction between mechanical output and physiological input (Barratt et al., 2016; Korff et al., 2007; Sunde et al., 2010). Theoretically, improving cycling economy elicits a better cycling time trial performance and/or less physiological demands (e.g., rate of oxygen consumption: V̇O2, heart rate) to complete at a given distance. The crank arm length (CAL) is one of the important factors among many variables that affect the economy and performance in cycling (McDaniel et al., 2002). Therefore, the appropriate selection of CAL may play a key role in improving the cycling portion of the race and entire triathlon performance. The purpose of this review is to identify the effects of acute changing CAL on physiological and biomechanical responses during cycling. Previous researchers have reported changing of CAL affect cycling power production (MacDermid & Edwards, 2010; Martin & Spirduso, 2001; Too & Landwer, 2000), lower limb joint angle, cadence (Barratt et al., 2011 & 2016; Candotti et al., 2007; Christiansen et al., 2013), pedal torque (Hull & Gonzalez, 1988), lower limb muscle activity (Watanabe, 2020), and V̇O2 (Ferrer-Roca et al., 2017; Morris & Londeree, 1997). The effect of different CALs on cycling power, lower extremity joint kinematics, and kinetics during such a short duration (~30 seconds) with supramaximal effort have been well documented (Barratt et al., 2011; Christiansen et al., 2013; MacDermid & Edwards, 2010; Martin & Spirduso, 2001; Too & Landwer, 2000; Watanabe, 2020). There is also a strong body of research that provides insight into the physiological and biomechanical responses according to acute changing of CALs at the constant work rate during submaximal cycling intensity (Barratt et al., 2016; Ferrer-Roca et al., 2017; Hull & Gonzalez, 1988; Korff et al., 2007; McDaniel et al., 2002). Some researchers have recommended using shorter CAL than conventional lengths (165~175mm) for generating more cycling power (Barratt et al., 2016; Hull & Gonzalez, 1988; Inbar et al., 1983). Ferrer-Roca et al. (2017) revealed the tendency of increasing hip and knee range of motion and hip extensor moment with a longer CAL than preferred CAL. However, other studies have been reported that there were no significant differences in cycling power, joint angle, and V̇O2 depends on when using different CALs (Barratt et al., 2011; Inbar et al., 1983; MacDermid & Edwards, 2010; McDaniel et al., 2002; Morris & Londeree, 1997; Watanabe, 2020). Furthermore, previous studies were limited in the type of subject recruited either elite or well-trained cyclists (Barratt et al., 2011 & 2016; Christiansen et al., 2013; Korff et al., 2007; MacDermid & Edwards, 2010; Martin & Spirduso, 2001; McDaniel et al., 2002; Morris & Londeree, 1997) or young healthy students (Ferrer-Roca et al., 2017; Hull & Gonzalez, 1988; Inbar et al., 1983; Too & Landwer, 2000; Watanabe, 2020). Some researchers have recommended using shorter CAL than conventional lengths (165~175mm) for generating more cycling power (Barratt et al., 2016; Hull & Gonzalez, 1988; Inbar et al., 1983). Ferrer-Roca et al. (2017) revealed the tendency of increasing hip and knee range of motion and hip extensor moment with a longer CAL than preferred CAL. However, other studies have been reported that there were no significant differences in cycling power, joint angle, and V̇O2 depends on when using different CALs (Barratt et al., 2011; Inbar et al., 1983; MacDermid & Edwards, 2010; McDaniel et al., 2002; Morris & Londeree, 1997; Watanabe, 2020). Furthermore, previous studies were limited in the type of subject recruited either elite or well-trained cyclists (Barratt et al., 2011 & 2016; Christiansen et al., 2013; Korff et al., 2007; MacDermid & Edwards, 2010; Martin & Spirduso, 2001; McDaniel et al., 2002; Morris & Londeree, 1997) or young healthy students (Ferrer-Roca et al., 2017; Hull & Gonzalez, 1988; Inbar et al., 1983; Too & Landwer, 2000; Watanabe, 2020). In this review, we focused on the effect of the acute changing of CAL on cycling. Even though ample research has been conducted to investigate the relationship between cycling performance and CAL in both biomechanics and exercise physiology perspectives, the effects of changing CAL on cycling time trial performance still remains unclear. Previous studies showed inconsistent results regarding the effect of changing CAL in cycling mechanic and physiological parameters. Increasing power output in a short duration may not a good indicator of cycling time trial performance. In terms of successful endurance cycling, the strategy to apply propulsion forces effectively over a long duration is more important than achieving a higher power output in a short amount of time. Furthermore, the maximum cycling power test mainly relies on anaerobic capacity (i.e., phosphagen & anaerobic glycolytic system); however, aerobic metabolism is a major energy source during endurance cycling from 80% up to 99% (Sunde et al., 2010). Therefore, the functional threshold power (FTP) test may be a better predictor of endurance cycling performance than the maximum power test in a short duration (Sørensen et al., 2019). Besides, a large range of CALs (110 to 265mm) was used for several studies that were impractical to use for cycling training and real race event. Based on the review of literature, the well-trained triathletes/cyclists could maintain approximately the same amount of cycling power output and V̇O2 across different CALs (Barratt et al., 2011; Watanabe, 2020). However, the changing of CALs may have more influence on the cycling economy and performance to novice triathletes/cyclists. Research by Martin and Spirduso (2001) demonstrated that the ratio between CAL and lower limb length for the maximal power production was 20% of leg length and 41% of tibia length, respectively. Also, this study showed an inverse relationship between cadence and speed depends on increasing CALs. Therefore, the aged group or novice triathletes should choose an appropriate CAL based on their lower limb length, cycling technique, and race strategies for better race performance. From these points of view, more research is needed about the effect of CAL in a standard range (165 ~ 175mm) on endurance cycling performance as an aspect of both biomechanical and physiological parameters. Also, future research will be testing the reliability of the effect of CAL on cycling mechanics and power output between the laboratory setting and overground.

Medicine & Science in Sports & Exercise

Journal of Health, Sports, and Kinesiology

Medicine & Science in Sports & Exercise

Journal of Health, Sports, and Kinesiology, 2021