Collegiate women's wrestling body fat percentage and minimum wrestling weight values: time for revisiting minimal body fat percent?

BACKGROUND

The estimation of body fat percentage (BF%) in wrestling is used to determine the minimum wrestling weight (MWW) and lowest allowable weight class (MWC) in which wrestlers are eligible to compete. A 12% minimum threshold is currently used for women wrestlers, yet a potential increase for safety has been discussed. Because of the novelty of collegiate women's wrestling, there is a paucity of literature available on the body composition norms of this population. The purpose of this study was to provide a descriptive summary of BF% and MWW values of female wrestlers and how MWW values would change with the use of different BF% thresholds.

METHODS

Data from the 2022-2023 collegiate season were retrospectively analyzed resulting in a sample of 1,683 collegiate women wrestlers from the National Association of Intercollegiate Athletics (NAIA, n = 868) and the National Collegiate Athletics Association (NCAA, n = 815). All wrestlers completed skinfold assessments for weight certification at the start of the competition season. The skinfold values were used to estimate BF% using the Slaughter skinfold prediction equation. Frequency statistics and descriptive analysis were performed to compute normative MWW and BF% profiles. BF% thresholds of 12% (12MWW) and the BF% value defined as the lowest 5th percentile, which would be considered unusually lean, were used to determine the resulting MWW and MWC for each method. The lowest recorded weight and weight class division throughout the season was also recorded for each wrestler.

RESULTS

There was a positively skewed (0.94) and platykurtic (1.86) distribution of MWW values. The median ± interquartile range BF% for all wrestlers was 27.4 ± 10.22%, with 17% BF representing the 5th percentile. Only 354 out of 1,579 (22.4%) wrestlers competed in their lowest allowable weight class, based on the 12MWW. Of these 354 wrestlers, the mean BF% was 21.3 ± 5.2% at weight certification with only n = 17 being at or below 12% body fat and an average weight loss of 11.1 ± 8.8 lbs. from the time of weight certification. Throughout the season, wrestlers competed at weights that were, on average (mean ± SD), 19.4 ± 16.9 lbs. higher than their 12MWW (95% CI: 18.6, 20.2 lbs. p < 0.001; effect size [ES] = 1.1), 13.4 ± 19.0 lbs. higher than the 17MWW (p < 0.001; ES = 0.70), and 8.7 ± 8.3 lbs. lower than their weight at the certification (95% CI: 8.3, 9.1 lbs. p < 0.001; ES = 1.1).

CONCLUSIONS

Nearly all BF% values were well above the 12% threshold used to determine MWW. Increasing the minimum BF% threshold from 12% to 17% would affect a small percentage of wrestlers, likely reduce the need for excessive weight cutting, and minimize the deleterious health effects of an athlete at such a low BF%.

The Effects of Protein and Carbohydrate Supplementation, with and without Creatine, on Occupational Performance in Firefighters

BACKGROUND

The purpose of this study was to assess the effects of protein and carbohydrate supplementation, with and without creatine, on occupational performance in firefighters.

METHODS

Using a randomized, double-blind approach, thirty male firefighters (age: 34.4 ± 8.4 yrs., height: 1.82 ± 0.07 m; weight: 88.6 ± 12.5 kg; BF%: 17.2 ± 5.8%) were randomized to receive either (A.) 25 g of whey protein isolate + 25 g of carbohydrate powder (ProCarb group); or (B.) ProCarb + 5 g of creatine (Creatine group) in a double-blind fashion over a period of 21-26 days (depending on shift rotations) to evaluate the impact of supplementation on occupation-specific performance. At baseline and following supplementation, firefighters completed a battery of tests. These tests included an aerobic speed test on an air-braked cycle ergometer followed by the hose carry, body drag, stair climb, and Keiser sled hammer for time.

RESULTS

No significant differences in measures of performance were observed at baseline (p > 0.05). There was a significant main effect for time observed for rescue, stair climb, total time to completion, and time trial performance (p < 0.05). There was a significant group × time (p < 0.05) interaction for rescue and forcible entry. Independent sample t-tests indicated that the Creatine group experienced a greater reduction (from baseline) in completion time for the rescue (1.78 ± 0.57 s, 95% CI: 0.61, 2.95 s, p = 0.004) and forcible entry (2.66 ± 0.97 s, 95% CI: 0.68, 4.65 s, p = 0.01) tests compared to the ProCarb group. No significant group × time interactions were observed for the hose line advance, stair climb, total time to completion, and time trial performance (p > 0.05).

CONCLUSIONS

The addition of supplemental creatine to a protein and carbohydrate supplement to the diet of career firefighters throughout a three week period improves occupational performance in firefighters in specific areas of high-intensity, repetitive actions.

Physiological Demands of a Self-Paced Firefighter Air-Management Course and Determination of Work Efficiency

Firefighters often complete air management courses (AMC) to assess the ability to tolerate personal protective equipment, appropriately manage the breathing system and assess occupational performance. Little information is known relative to the physiological demands of AMCs, nor how to assess work efficiency in order to characterize occupational performance and evaluate progress.

PURPOSE

To assess the physiological demands of an AMC and examine differences across BMI categories. A secondary aim was to develop an equation to assess work efficiency in firefighters.

METHODS

Fifty-seven firefighters (Women, n = 4; age: 37.2 ± 8.4 yr.; height: 182.0 ± 6.9 cm; body mass: 90.8 ± 13.1 kg; BMI: 27.8 ± 3.6 kg·m^-2) completed an AMC per routine evaluation while wearing a department issued self-contained breathing apparatus and full protective gear. Course completion time, starting pounds per square inch (PSI) on the air cylinder, changes in PSI, and distance traveled were recorded. All firefighters were equipped with a wearable sensor integrated with a triaxial accelerometer and telemetry to assess movement kinematics, heart rate, energy expenditure, and training impulse. The AMC consisted of an initial section involving a hose line advance, rescue (body drag), stair climb, ladder raise, and forcible entry. This section was followed by a repeating loop, which consisted of a stair climb, search, hoist, and recovery walk. Firefighters repeated the course loop until the self-contained breathing apparatus air supply pressure reached 200 PSI, at which time they were instructed to lay down until the PSI reached zero.

RESULTS

Average completion time was 22.8 ± 1.4 min, with a mean distance of 1.4 ± 0.3 km and an average velocity of 2.4 ± 1.2 m·s^-1. Throughout the AMC, the mean heart rate was 158.7 ± 11.5 bpm equating to 86.8 ± 6.3% of the age-predicted max heart rate and a training impulse of 55 ± 3 AU. Mean energy expenditure was 464 ± 86 kcals and work efficiency was 49.8 ± 14.9 km·PSI^-1·s. Regression analysis determined that fat-free mass index (R² = 0.315; β = -5.069), body fat percentage (R² = 0.139; β = -0.853), fat-free mass (R² = 0.176; β = -0.744), weight (R² = 0.329; β = -0.681), and age (R² = 0.096; β = -0.571) were significant predictors of work efficiency.

CONCLUSIONS

The AMC is a highly aerobic task with near-maximal heart rates reached throughout the course. Smaller and leaner individuals achieved a higher degree of work efficiency during the AMC.

Tracking the Fatigue Status after a Resistance Exercise through Different Parameters

The purpose of the study was to investigate the sensitivity of back squat bar velocity, isometric mid-thigh pull, heart rate variability parameters, perceived recovery scale and step counts for tracking the muscular fatigue time-course (reduction in countermovement jump [CMJ] performance) after strenuous acute lower limb resistance exercise. Sixteen healthy men performed heart rate variability assessment, perceived recovery scale, CMJ, back squat bar velocity, isometric mid-thigh pull, and daily step counts before and 24 h, 48 h and 72 h post a strenuous acute lower limb resistance exercise (8×10 repetitions). The CMJ height decreased at 24 and 48 h after exercise session (p≤0.017), evidencing the muscular fatigue. The perceived recovery scale presented lower values compared to baseline until 72 h after exercise session (p<0.001 for all). The heart rate variability parameters and step counts were not significantly different across time. At 24 h post, only mean force of mid-thigh pull was decreased (p=0.044), while at 48 h post, only peak force of mid-thigh pull was decreased (p=0.020). On the last day (72 h), only bar velocity (mean) presented reduction (p=0.022). Therefore, the perceived recovery scale was the only variable sensible to tracking muscular fatigue, i. e. presenting a similar time-course to CMJ height.

The Effect of Set Configuration and Load on Post-Activation Potentiation on Vertical Jump in Athletes

The aim of this study was to compare the effect of post-activation potentiation (PAP) on countermovement jump (CMJ) using different set configurations and loads on conditioning activity (CA) in highly trained athletes. Sixteen national level swimmers participated in this study and performed a total of six visits to the laboratory. The first session was used for familiarization, the second session was utilized to determine five repetitions maximum (RM) in the half squat (HS), and the following four visits consisted of four CA protocols performed in a counterbalanced order. Two CAs were performed as traditional sets (TS) with sequential repetition, with different load, which involved one set of five repetitions at 100% (TS100) or 65% of 5 RM load (TS65). Additionally, two CAs included one set of five repetitions with intraset rests, 30 second inter-repetition rest (IRR), with both relative loads (IRR100 and IRR65). Countermovement jump height was measured at baseline, immediately after the CA, and every two-minutes until twelve-minutes. Significantly faster peak and mean barbell velocity was observed for the CAs with lower relative loads (p < 0.05). When evaluating the best result at individual time point of CMJ height after the CA, TS100 improved CMJ performance (ES = 0.38, p = 0.028, Δ% = 4.8 ± 7.3). Thus, set configuration using IRR does not promote PAP in the current study and TS with a high-load should be adopted for an acute improvement in CMJ for highly trained athletes.

Profiles of Heart Rate Variability and Bar Velocity after Resistance Exercise

INTRODUCTION

The aim of this investigation was to observe the association in the time course in recovery between multiple heart rate variability (HRV) metrics and neuromuscular performance, as assessed by mean bar velocity (BVM) in the back squat, over a 72-h period after an exhaustive back squat protocol.

METHODS

Eight resistance-trained males completed five laboratory visits within a 7-d period. The first visit involved short-term HRV recordings followed by a familiarization of BVM procedures and a one-repetition maximum test of the back squat. Forty-eight hours later, participants returned to the laboratory for prestimulus measurements, immediately followed by a back squat protocol (8 sets of 10 repetitions at 70% of one-repetition maximum with a 2-min rest). The HRV and the BVM measurements were replicated at 0.5, 24, 48, and 72 h after squat protocol. A multivariate profile analysis and repeated-measures correlation between recovery scores [(new/prestimulus) × 100] for each HRV metric and BVM was computed.

RESULTS

All log-transformed (ln) HRV metrics, except low frequency (lnLF) (P = 0.051), had a significant interaction with BVM over time (P < 0.05), indicating that recovery scores in BVM and HRV were not parallel. In addition, recovery scores in all HRV metrics significantly differed from BVM (P < 0.05) in at least one time point across the 72-h period. Furthermore, repeated-measures correlation analysis indicated a lack of intraindividual association (P > 0.05) between the change in BVM and all HRV measurements over time.

CONCLUSION

The time course in recovery in HRV measurements after an exhaustive bout of lower-body resistance exercise was not associated with neuromuscular performance recovery.

Effect of Postactivation Potentiation on Explosive Vertical Jump: A Systematic Review and Meta-Analysis

Dobbs, WC, Tolusso, DV, Fedewa, MV, and Esco, MR. Effect of postactivation potentiation on explosive vertical jump: a systematic review and meta-analysis. J Strength Cond Res 33(7): 2009-2018, 2019-The primary aim of this systematic review and meta-analysis was to quantify the magnitude of the effect of postactivation potentiation (PAP) on explosive vertical power while accounting for the nesting of multiple effects within each study. This study was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis Statement (PRISMA). Original research articles published by January 18, 2018, were located using an electronic search of 4 databases and yielded 759 original publications. Data were extracted and independently coded by 2 authors (W.C.D. and D.V.T.). The standardized mean effect size (ES) was calculated by subtracting the pre-treatment mean from the post-treatment mean and dividing by the pooled SD, adjusting for small sample bias. Multilevel random-effects model was used to aggregate a mean ES and 95% confidence interval (CI) for PAP on vertical jump performance. The cumulative results of 179 effects gathered from 36 studies indicate that PAP does not improve vertical jump performance (ES = 0.08, 95% CI -0.04 to 0.21, p = 0.197), with moderate heterogeneity. Moderator analysis indicated that rest intervals between 3 and 7 minutes provided favorable performance outcomes (ES = 0.18, 95% CI 0.05 to 0.31, p = 0.007). Conversely, rest intervals less than 3 minutes (ES = -0.15, 95% CI -0.31 to 0.01, p = 0.052) or performing isometric contractions (ES = -0.52, 95% CI -0.89 to -0.14, p = 0.007) may be detrimental to performance. Meta-regression indicated that rest interval was the only moderator significantly associated with ES (β = -0.04, 95% CI -0.57 to -0.02, R = 14.31%, p < 0.001). When appropriate PAP guidelines are followed, an increase in vertical jump performance may be achieved.

The Effect of Chronic Exercise Training on Leptin: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

BACKGROUND

Leptin is a hormone associated with satiety, lipid oxidation, energy expenditure, and energy homeostasis. To date, the current body of research examining the effect of chronic exercise training on leptin has yielded inconsistent results.

OBJECTIVE

The purpose of this meta-analysis was to provide a quantitative estimate of the magnitude of change in leptin levels following participation in exercise interventions lasting ≥ 2 weeks.

METHODS

All studies included were peer-reviewed and published in English. To be included, studies randomized human participants to an exercise training group or non-exercise comparison group for an exercise training intervention. Leptin levels were measured at baseline, during, and/or after completion of the exercise training program. Random-effects models were used to aggregate a mean effect size (ES) and 95% confidence intervals (CIs), and identify potential moderators.

RESULTS

Seventy-two randomized controlled trials met the inclusion criteria and resulted in 107 effects (n = 3826). The mean ES of 0.24 (95% CI 0.16-0.32, p < 0.0001) indicated a decrease in leptin following an exercise training program. A decrease in %Fat (β = - 0.07, p < 0.01) was associated with a decrease in leptin after accounting for the type of control group (β = - 0.38, p < 0.0001) used in each study.

CONCLUSION

These results suggest that engaging in chronic exercise training (≥ 2 weeks) is associated with a decrease in leptin levels for individuals regardless of age and sex. However, a greater decrease in leptin occurred with a decreased percentage of body fat.

The Predictability of Peak Oxygen Consumption Using Submaximal Ratings of Perceived Exertion in Adolescents

Rating of perceived exertion (RPE) extrapolation involves mathematically extending the submaximal relationship between RPE and oxygen consumption (VO2) to maximal intensity. This technique allows practitioners to forego, potentially dangerous, maximal exertion testing while attaining accurate measures of maximal oxygen consumption used for exercise prescription. This method has been proven accurate in adults, but much less in known when applied to an adolescent population. The purpose of this study was to assess the accuracy of the RPE extrapolation as method for estimating VO2max in adolescents. Twenty-two healthy, asymptomatic adolescents performed a graded exercise test (GXT) to exhaustion. Heart rate and VO2 were recorded throughout the bout with RPE being queried every two minutes using the Borg (6-20) RPE scale. Individual regression lines were fitted for each subject using RPE and VO2 for RPE values up to 13,15, and 17. Theoretical maximal RPE values of 20 and 19 were entered into the equation to calculate an estimated VO2max. Repeated measures ANOVA with planned contrasts showed that all VO2max estimation methods significantly overpredicted measured VO2max (p < .001). Error analysis via Bland-Altman plots revealed large limits of agreement between the all methods, indicating large variability in error between estimated and measured VO2max. The results suggest that submaximal RPE values using the Borg scale cannot be used to predict VO2max in children due to the amount of error in the prediction equations. These inaccuracies could lead to potential under or over-prescription of exercise intensity and adverse effects on the person's health.