The Relationship Between Aerobic and Anaerobic Performance in Recreational Runners

International Journal of Exercise Science 9(5): 625-634, 2016. Research has indicated that combined aerobic and anaerobic training (concurrent training) may improve aerobic performance greater than aerobic training alone. The purpose of this investigation was to establish any associations between aerobic and anaerobic performance. Eleven participants (n = 11, age = 34.1 ± 13 years, VO2max = 58.4 ± 7.8) volunteered for this study. Participants were asked for endurance training experience (4.7 ± 3.7 years) and resistance training experience (4.1 ± 4.6 years). To meet training status, participants were to have a VO2max in the 80th percentile as per ACSM guidelines. The Bruce treadmill test was used to measure aerobic performance. In order to measure anaerobic performance, several tests were completed utilizing a force platform. A Pearson Product R Correlation Coefficient was calculated to determine correlations between variables. The results show significant correlation between VO2max and RFD (r = 0.68). Further analyses utilizing Cohen’s effect size indicated a strong association between VO2max and peak force, as well as running efficiency and peak power, relative peak power, and power endurance. These results indicate an existing possibility that anaerobic performance measures such as RFD may have a positive relationship with aerobic performance measures such as VO2max. Therefore, it may be beneficial to integrate specific training components which focus on improving RFD as a method of improving running performance

Endogenous versus exogenous carbohydrate oxidation measured by stable isotopes in pre-pubescent children plus 13C abundances in foods consumed three days prior

Purpose: The purposes of the present study were to (a) examine resting metabolism, substrate utilization, and endogenous versus exogenous carbohydrate (CHO) oxidation before and after 30-g rapidly-digesting carbohydrate (RDC) ingestion using indirect calorimetry and breath test analysis of stable isotope concentrations in pre-pubescent children and (b) report the 13C abundances in foods consumed for three days prior. Methods: Nineteen children (n 1⁄4 10 boys, n 1⁄4 9 girls) at Tanner stage I or II participated (mean age ± 95% CI 1⁄4 9.84 ± 0.77 y) in this study. Food was administered to the children for three days preceding their scheduled breath tests. Breath tests and indirect calorimetry were performed after an 8-h fast before and 60 min following consumption of a 30-g simple RDC drink consisting of maltodextrin and sucrose. Open circuit spirometry and indirect calorimetry monitored resting metabolism and CHO oxidation. Separate breath samples were taken every 15 min. Samples of all foods and breath samples were analyzed for 13C and 12C abundances with a stable-isotope mass spectrometer. Results: 13C in expired breath samples were 23.81 + 1.64‰ at baseline and increased every 15 min after consumption of the CHO drink (p \u3c 0.001e0.009). Cumulative total, endogenous, and exogenous CHO utilization increased during the post-prandial period (p \u3c 0.001). Endogenous CHO oxidation was consistently greater than exogenous CHO oxidation (p \u3c 0.001e0.002). Blood glucose was elevated from baseline at 30- and 60-min post-prandial (p \u3c 0.001). Insulin did not change over time (p 1⁄4 0.184). Conclusions: The foods provided during the 3-day controlled diet effectively minimized 13C variation prior to metabolic testing. The 13C abundances of foods reported herein should serve as practical recommendations to reduce 13C intake before breath tests. While endogenous CHO oxidation remained greater in proportion to exogenous CHO oxidation, these findings suggest that even a relatively small amount of RDC can increase exogenous CHO oxidation and blood glucose in normal-weight children. To further examine shifts in endogenous versus exogenous CHO utilization, we recommend that future studies take steps to minimize 13C variation before breath tests and examine changes in substrate metabolism at rest and during exercise in normal weight and overweight pre-pubescent children. Clinical trial registration number: NCT03185884

Comparisons of Muscle Strength, Size, and Neuromuscular Function in Pre- and Post-pubescent Males and Females

The purpose of this study was to compare measurements of muscle strength, size, and neuromuscular function of the forearm flexors in pre- and post-pubescent males and females. Forty pre-pubescent (mean ± 95% confidence interval, age = 9.79 ± 0.35 yrs, n = 10 males, n = 10 females) and post-pubescent (age = 17.23 ± 0.58 yrs, n = 10 males, n = 10 females) participants completed this study. Biceps brachii muscle cross-sectional area (CSA) and muscle volume (MV) were quantified from ultrasound images. Participants completed maximal voluntary isometric contractions (MVICs) of the forearm flexors and extensors, and submaximal isometric step muscle actions at 30, 50, and 70% of the peak MVIC, as well as one absolute low-level torque step muscle action that equaled 5 Nm. Participants also completed isometric ramp muscle actions at a constant rate of torque increase (7.5 Nm∙s-1). Percent voluntary activation (VA) was quantified during the MVIC and submaximal isometric step muscle actions, while EMG amplitude and MMG amplitude were quantified during the isometric ramp muscle actions. MVIC strength was expressed in absolute terms and normalized to CSA and MV to examine the influence of muscle size on differences in strength between groups. The post-pubertal males were 130% stronger, had 78% greater CSA, 374% greater MV, and 17% greater maximal VA than the pre-pubertal males, while the post-pubertal females were 72% stronger, had 63% greater CSA, 270% greater MV, and 23% greater maximal VA than the pre-pubertal females. Normalizing MVIC strength to CSA and MV accounted for a greater proportion of the difference in strength between males than females. The collective responses for VA, EMG amplitude, and MMG amplitude across intensity reflected differences in muscle activation and motor unit recruitment strategies between pre- and post-pubertal males and females. These results suggest that muscle size may account for a greater proportion of the growth and development-related differences in strength among males, while females may be more affected by changes in muscle activation. However, regardless of sex, changes in muscle size and neuromuscular function occur during growth and development. Advisor: Joel T. Crame

Comparisons of Muscle Strength, Size, and Neuromuscular Function in Pre- and Post-Pubescent Males and Females

The purpose of this study was to compare measurements of muscle strength, size, and neuromuscular function of the forearm flexors in pre- and post-pubescent males and females. Forty pre-pubescent (mean ± 95% confidence interval, age = 9.79 ± 0.35 yrs, n = 10 males, n = 10 females) and post-pubescent (age = 17.23 ± 0.58 yrs, n = 10 males, n = 10 females) participants completed this study. Biceps brachii muscle cross-sectional area (CSA) and muscle volume (MV) were quantified from ultrasound images. Participants completed maximal voluntary isometric contractions (MVICs) of the forearm flexors and extensors, and submaximal isometric step muscle actions at 30, 50, and 70% of the peak MVIC, as well as one absolute low-level torque step muscle action that equaled 5 Nm. Participants also completed isometric ramp muscle actions at a constant rate of torque increase (7.5 Nm∙s-1). Percent voluntary activation (VA) was quantified during the MVIC and submaximal isometric step muscle actions, while EMG amplitude and MMG amplitude were quantified during the isometric ramp muscle actions. MVIC strength was expressed in absolute terms and normalized to CSA and MV to examine the influence of muscle size on differences in strength between groups. The post-pubertal males were 130% stronger, had 78% greater CSA, 374% greater MV, and 17% greater maximal VA than the pre-pubertal males, while the post-pubertal females were 72% stronger, had 63% greater CSA, 270% greater MV, and 23% greater maximal VA than the pre-pubertal females. Normalizing MVIC strength to CSA and MV accounted for a greater proportion of the difference in strength between males than females. The collective responses for VA, EMG amplitude, and MMG amplitude across intensity reflected differences in muscle activation and motor unit recruitment strategies between pre- and post-pubertal males and females. These results suggest that muscle size may account for a greater proportion of the growth and development-related differences in strength among males, while females may be more affected by changes in muscle activation. However, regardless of sex, changes in muscle size and neuromuscular function occur during growth and development

Comparisons of Muscle Strength, Size, and Neuromuscular Function in Pre- and Post-Pubescent Males and Females

The purpose of this study was to compare measurements of muscle strength, size, and neuromuscular function of the forearm flexors in pre- and post-pubescent males and females. Forty pre-pubescent (mean ± 95% confidence interval, age = 9.79 ± 0.35 yrs, n = 10 males, n = 10 females) and post-pubescent (age = 17.23 ± 0.58 yrs, n = 10 males, n = 10 females) participants completed this study. Biceps brachii muscle cross-sectional area (CSA) and muscle volume (MV) were quantified from ultrasound images. Participants completed maximal voluntary isometric contractions (MVICs) of the forearm flexors and extensors, and submaximal isometric step muscle actions at 30, 50, and 70% of the peak MVIC, as well as one absolute low-level torque step muscle action that equaled 5 Nm. Participants also completed isometric ramp muscle actions at a constant rate of torque increase (7.5 Nm∙s-1). Percent voluntary activation (VA) was quantified during the MVIC and submaximal isometric step muscle actions, while EMG amplitude and MMG amplitude were quantified during the isometric ramp muscle actions. MVIC strength was expressed in absolute terms and normalized to CSA and MV to examine the influence of muscle size on differences in strength between groups. The post-pubertal males were 130% stronger, had 78% greater CSA, 374% greater MV, and 17% greater maximal VA than the pre-pubertal males, while the post-pubertal females were 72% stronger, had 63% greater CSA, 270% greater MV, and 23% greater maximal VA than the pre-pubertal females. Normalizing MVIC strength to CSA and MV accounted for a greater proportion of the difference in strength between males than females. The collective responses for VA, EMG amplitude, and MMG amplitude across intensity reflected differences in muscle activation and motor unit recruitment strategies between pre- and post-pubertal males and females. These results suggest that muscle size may account for a greater proportion of the growth and development-related differences in strength among males, while females may be more affected by changes in muscle activation. However, regardless of sex, changes in muscle size and neuromuscular function occur during growth and development

State Population Influences Athletic Performance Combine Test Scores in High School-Aged American Football Players

This study compared athletic performance differences among high school American football combine participants originating from states of different population sizes. High school-aged American football players (n=7,214) who had participated in athletic performance combines between March 2015 and January 2016 were included in this analysis. Data included combine date and location, school state of origin, football position, class, height, weight, 10-, 20-, and 40-yd dash times, pro-agility, L-cone drill, vertical jump, broad jump, and power push-up. Participants were separated into high- (state population\u3e10,000,000; HIGH; n=2,804), mid- (state population=5,000,000-9,999,999; MID; n=2,911), or low-population (state population\u3c5,000,000; LOW; n=1,499) state of origin. Data were allometrically scaled to account for differences in body mass across high school grade levels and American football positions. All statistical analyses were performed on the allometrically scaled data. LOW athletes performed better than HIGH athletes in the 20-yd dash (p≤0.01). LOW athletes performed better than HIGH and MID in the 40-yd dash, proagility, broad jump, and power push-up (p\u3c0.01). LOW and HIGH athletes performed better than MID in the Lcone and vertical jump (p\u3c0.01). When considering population size, athletes originating from LOW states may demonstrate higher levels of athletic performance in football combine events hypothetically due to more opportunities for sports participation and playing time, leading to greater athletic development. Youth and high school coaches in MID and HIGH states might consider providing more opportunities for playing and individualized coaching to encourage long-term athletic development

State Population Influences Athletic Performance Combine Test Scores in High School-Aged American Football Players

International Journal of Exercise Science 12(6): 256-262, 2019. This study compared athletic performance differences among high school American football combine participants originating from states of different population sizes. High school-aged American football players (n=7,214) who had participated in athletic performance combines between March 2015 and January 2016 were included in this analysis. Data included combine date and location, school state of origin, football position, class, height, weight, 10-, 20-, and 40-yd dash times, pro-agility, L-cone drill, vertical jump, broad jump, and power push-up. Participants were separated into high- (state population\u3e10,000,000; HIGH; n=2,804), mid- (state population=5,000,000-9,999,999; MID; n=2,911), or low-population (state population\u3c5,000,000; LOW; n=1,499) state of origin. Data were allometrically scaled to account for differences in body mass across high school grade levels and American football positions. All statistical analyses were performed on the allometrically scaled data. LOW athletes performed better than HIGH athletes in the 20-yd dash (p≤0.01). LOW athletes performed better than HIGH and MID in the 40-yd dash, pro-agility, broad jump, and power push-up (p\u3c0.01). LOW and HIGH athletes performed better than MID in the L-cone and vertical jump (p\u3c0.01). When considering population size, athletes originating from LOW states may demonstrate higher levels of athletic performance in football combine events hypothetically due to more opportunities for sports participation and playing time, leading to greater athletic development. Youth and high school coaches in MID and HIGH states might consider providing more opportunities for playing and individualized coaching to encourage long-term athletic development

Stature, Body Mass, and BMI in High School American Football Players: Appropriate determinants of obesity prevalence?

The purpose of this study was to evaluate stature (HT), weight (WT), body mass index (BMI), and obesity prevalence based on BMI categories in a large sample (n = 7,175) of high school American football players enrolled as freshmen, sophomores, or juniors. Players were categorized by their positions: offensive linemen (OL), defensive linemen (DL), tight end (TE), defensive end (DE), linebacker (LB), running back (RB), quarterback (QB), defensive back (DB), and wide receiver (WR). HT, WT, and BMI increased as grade increased among all positions. OL and DL had the greatest HT, WT, and BMI (p≤0.05). Obesity prevalence was greatest in OL and DL. When accounting for age-related increases in BMI, WT increased to a greater degree than HT. If HT is an indirect indicator of skeletal size, while WT is more influenced by soft tissue, then the age-related BMI increases in the present study may be largely accounted for by soft tissue changes rather than skeletal growth. Even though obesity prevalence in OL (94.5%) and DL (78.4%) positions was greater than all other positions as determined from BMI, it is impossible to know the allocations of fat-free and fat mass—particularly in American football athletes. If obesity continues to be defined as an unhealthy accumulation of fat, then athletes who may have a greater relative proportion of lean soft tissue should not be classified as obese using BMI (WT÷HT²). More sophisticated, reliable, and sensitive measure of body composition, such as skinfolds, may be more appropriate field measurements