Revisiting the Assessment of Strength, Power, and Change of Direction in Collegiate American Football Athletes.

ABSTRACT: Burke, AA, Guthrie, BM, Magee, M, Miller, AD, and Jones, MT. Revisiting the assessment of strength, power, and change of direction in collegiate american football athletes. J Strength Cond Res 37(8): 1623-1627, 2023-The primary purpose was to assess the effect of strength on vertical jump (VJ) and change of direction (COD) with a secondary purpose to examine if these relationships were moderated by the sport position group through path analysis using structural equation modeling. Subjects were collegiate American football athletes grouped by skill (SK; n = 98) and nonskill (NS; n = 83) sport position groups. Maximal strength was assessed by 1 repetition maximum back squat and hang clean (HC). Vertical jump was used to evaluate power. Change of direction was assessed through the 20-yard shuttle (i.e., 5-10-5) test. Multigroup path analysis examined causal pathways among variables and moderating effects of sport position. The final model revealed that VJ fully mediated the relationship between HC and COD (HC-VJ: ß = 0.408, p < 0.001; VJ-COD: ß = -0.376, p < 0.001; and HC-COD: ß = -0.137, p = 0.17) in SK. The NS showed only direct effects of HC on COD ( ß = -0.335, p < 0.001). These findings suggest that strength does not solely explain COD ability but also can serve to enhance underpinning qualities, such as relative force production in the VJ. Relationships between strength, power, and COD are different depending on the positional group. The results provide further insight into performance outcomes in field tests. It is recommended that sport position differences be considered when assessing and analyzing physical qualities in a team setting within the sport of American football.

Upper body push to pull ratios in law enforcement officer recruits.

BACKGROUND: Law enforcement recruits (LER) often encounter shoulder injuries, which may cause attrition from academies. Investigating required upper body muscular fitness may inform of muscular balance around shoulder joints through anterior and posterior ratios in LER. OBJECTIVE: To investigate push to pull ratios (P2P) and factors related with P2P in LER. METHODS: LER (95 males; 12 females) completed testing during a single session in the academy's first week: body mass, one-repetition maximum (1RM) bench press, push-up repetitions (reps) to failure, and pull-up reps to failure. Calculations were: estimated pull-up 1RM=body mass+0.033*(body mass x pull-ups); endurance P2P (eP2P)=push-ups / pull-ups; strength P2P (sP2P)=bench press 1RM / estimated pull-up 1RM. Pearson correlation coefficients assessed relationships among tests and P2P (p < 0.05). RESULTS: The sP2P was positively correlated with bench press 1RM and push-ups. The eP2P was negatively associated with pull-up reps and 1RM. Females had similar eP2P, but lower sP2P than male recruits (p < 0.05). CONCLUSION: Practitioners may benefit from examining eP2P and sP2P as they should not be used interchangeably. Future research should examine whether the P2P ratios are associated with injury and subsequent inability to successfully complete law enforcement training academies.

What Factors Predict Upper Body Push to Pull Ratios in Professional Firefighters?

Shoulder joint injuries are common for professional firefighters. A potential cause of shoulder injury is an imbalance between anterior (push) and posterior (pull) shoulder joint musculature. Understanding what contributes to these imbalances may help to identify areas needing improvement. The purpose of this study was to investigate different push to pull (P2P) ratios and the relationships among common upper body fitness assessments, body composition, and push to pull (P2P) ratios in firefighters. Thirty-three professional firefighters completed the following testing protocol: one-repetition maximum (1RM) bench press, pull-up repetitions to failure, push-up repetitions to failure, and a body composition assessment. The endurance P2P (eP2P) was computed by dividing the number of push-up by pull-up repetitions, while strength P2P (sP2P) was the relative 1RM divided by pull-up repetitions. Bivariate relationships among variables were assessed with correlation coefficients and linear regression assessed association between eP2P and sP2P (p ≤ 0.05). The sP2P and eP2P were not associated (R 2 = 0.032, p = 0.99). Strength P2P was related with bench press 1RM (r = 0.80) and push-ups (r = 0.40). Endurance P2P was related with pull-up repetitions (r = -0.62), body fat percentage (r = 0.40), and fat mass index (r = 0.34). The results of the present study suggest sP2P and eP2P ratios should not be used interchangeably. To improve sP2P and eP2P for firefighters, it is recommended to improve the strength of anterior and posterior upper body musculature, respectively, and reduce total body fat mass.

The Effects of Whole-Body Photobiomodulation Light-Bed Therapy on Creatine Kinase and Salivary Interleukin-6 in a Sample of Trained Males: A Randomized, Crossover Study.

Photobiomodulation therapy (PBMT) can be applied to the whole body as compared to the application of using single hand-held devices that isolate a smaller muscle area. The purpose of this study was to examine the effects of an acute dose of whole-body PBMT pre- and post-high-intensity resistance training on creatine kinase (CK) and salivary interleukin-6 (IL-6) in a sample of trained males. Twelve males (31 ± 8.3 years, 177.2 ± 5.4 cm, and 86.0 ± 7.5 kg) were part of a randomized, counterbalanced, cross-over design, whereby each participant performed a high-intensity resistance training session that consisted of the bench press, chin-up, and repeated sprints on two separate occasions. Each participant was assigned to either the PBMT or control condition on two separate weeks, with a 10-days washout period between the weeks. Creatine kinase was measured at baseline, 24, 48, and 72 h post-exercise. Salivary IL-6 was measured at baseline, 60, 90, and 120 min. A paired t-test showed no significant difference (p = 0.669) in the area under the curve (AUC) for CK during the PBMT (191.7 ± 48.3) and control conditions (200.2 ± 68.0). A Wilcoxon signed-rank test also showed no significant median difference (p = 0.155) in the AUC for salivary IL-6 during the PBMT (Mdn = 347.7) and control conditions (Mdn = 305.8). An additional Wilcoxon signed-rank test for CK percentage change from 24 to 72 h showed the PBMT condition (Mdn = -45%) to have a -18% median difference as compared to the control condition (Mdn = -41%). As such, whole-body PBMT does not significantly reduce the activity of salivary IL-6 or CK concentration during the 24 to 72-h recovery post-high-intensity resistance training.