Correlation between lower limb and trunk muscle endurance with drop vertical jump in the special military forces.

OBJECTIVE: Police officers, particularly the ones who are trained to be on "special forces", perform a wide range of hazardous and physically demanding activities when aiming to protect and serve. The purpose of this study was to investigate the association between lower limb and trunk muscle endurance with drop vertical jump (DVJ) height in a special military police force. METHODS: One hundred and three male military men (age: 36 ± 5.0 years; height: 1.76 ± 0.05 m; weight: 81.8 ± 9.7 kg) volunteered to take part in this study. SIX TESTS WERE PERFORMED: DVJ, McGill core battery (trunk flexion, trunk extension, and side bridge test-right and left), and single-leg squat repetitions. Correlations were analyzed using the Pearson correlation coefficient (r). The level of significance for all analyses was set at p ≤ 0.05. RESULTS: Single-leg squat repetitions were positively associated with DVJ height, contact time and flight time (p = 0.00093∗∗, p = 0.00085∗∗, and p = 0.00098∗∗ respectively). No correlation was observed between trunk muscle endurance and DVJ. CONCLUSION: Therefore, it was concluded that greater endurance of the lower limb muscles, as demonstrated by the single leg squat, was associated with better performance in a DVJ. Individuals should consider incorporating single leg squats into their fitness program to develop muscular endurance and possibly perform better in the DVJ.

The Effect of Different Rest Intervals Between Agonist-Antagonist Paired Sets on Training Performance and Efficiency.

ABSTRACT: Behenck, C, Sant'Ana, H, Pinto de Castro, JB, Willardson, JM, and Miranda, H. The effect of different rest intervals between agonist-antagonist paired sets on training performance and efficiency. J Strength Cond Res 36(3): 781-786, 2022-The purpose of this study was to verify the effect of different rest intervals (RIs) between agonist-antagonist paired sets (APS) on training performance and efficiency. Eighteen recreationally trained men (age: 21.5 ± 2.1 years, body mass: 74.5 ± 10.4 kg, height: 1.75 ± 0.04 m, body mass index: 24.4 ± 3.7 kg·m-2) completed 4 sessions. During each session, a 10-repetition maximum load was used for 3 APS of Bench Row + Bench Press and Lat Pull-down + Overhead Press with RI between APS sequences of 1, 2, 3 minutes (min) or self-selected RI (SRI). Total training volume (TTV), session time and efficiency were measured in all sessions. The 1-minute RI resulted in significantly less TTV vs. the other conditions (p = 0.000). The 2-minute RI resulted in significantly less TTV vs. the 3-minute RI (p = 0.002), but the SRI was not significantly different vs. the 3-minute RI. For session time, the 1-minute RI was significantly less (p = 0.000) and the 3-minute RI was significantly greater (1-minute and 2-minute RI, p = 0.000; SRI, p = 0.010) than the other conditions. Therefore, the efficiency of the 1-minute RI was significantly greater vs. the other conditions (3-minute RI and SRI, p = 0.000; 2-minute RI, p = 0.001) and the 2-minute RI was significantly greater vs. the 3-minute RI (p = 0.001). There were no significant differences in TTV, session time, and efficiency between the 2-minute RI and SRI conditions. In conclusion, the 2-minute RI and SRI conditions may present a better cost-effectiveness. It is suggested that self-selected RI can provide better performance, whereas 2-minute RI may enable greater efficiency.

Correlation between pain, anthropometric measurements, stress and biochemical markers in women with low back pain.

Aim: To analyze the associations between pain duration, pain levels, anthropometric measures, perceived stress and biochemical markers in women with low back pain. Materials & methods: Forty-two participants were submitted to body mass, height, abdominal circumference, cortisol and creatine kinase (CK) collections. Pain duration, pain levels and stress were analyzed through specific questionnaires. Results: There were positive correlations between abdominal circumference and body mass, duration of pain and age, abdominal circumference, CK and age, CK and BMI, CK and abdominal circumference, and CK and duration of pain (p < 0.05). Conclusion: The higher the level of tissue damage over the years, the greater the tendency for higher levels of low back pain perception. Central fat was related to greater load on the spine.

Lay abstract Low back pain (LBP) is one of the factors that hinders the routine and productivity of women. LBP can cause functional disability and negatively interfere with work activities. The increase in pain can be caused by mechanical postural factors (such as behavioral habits), traumatic (such as accidents), and psychosocial factors (such as physical inactivity). Chronic LBP can influence behavioral aspects due to adaptations of pain feedback, such as postures to avoid pain and sedentary lifestyle. In this study, we observed that duration of LBP was related to higher levels of creatine kinase, which is an enzyme of our body that can be related to tissue damage. Moreover, the abdominal circumference, due to the accumulation of fat in this region, presented correlation with higher levels of tissue damage by creatine kinase and longer exposure time with LBP.

Myoelectric activity of the gastrocnemius during plantar flexion in a standing versus seated position and with a neutral or dorsiflexed ankle: A pilot study.

OBJECTIVE: The purpose of this study was to investigate the surface electromyographic (EMG) activity of the medial (GM) and lateral (GL) heads of the gastrocnemius muscle during plantar flexion performed in standing or seated positions, and with a neutral or dorsiflexed ankle. INTRODUCTION: The tríceps surae (gastrocnemius and soleus) is an essential muscle group that promotes propulsion during walking, running and tasks of daily living. METHODS: Ten male volunteers (24.5 ± 3.6 years, weight: 75.8 ± 10 kg; height: 1.74 ± 0.07 m) performed ten repetitions of plantar flexion under four different conditions: a) standing position (SP); b) standing position with passive stretch of the gastrocnemius muscle (SPS); c) seated with the knee flexed (KF); d) seated with the knee flexed and a passive stretch of the gastrocnemius (KFS). RESULTS: The muscle activity expressed as the root mean square (RMS) was significantly higher for the GL in the SPS versus the SP condition, while there was no difference for the GM between conditions. However, for the KF condition, GM activity was significantly higher versus the KFS condition, which was not verified for the GL. CONCLUSIONS: Therefore, the standing position with passive stretching of the triceps surae may be more efficient in increasing the myoelectric activity of the GL. However, the sitting position without passive stretching promoted greater GM muscle recruitment. The length/tension relationship of gastrocnemius could be used as a prescription variable during rehabilitation or conditioning programs.

Effects of physical exercise on low back pain and cortisol levels: a systematic review with meta-analysis of randomized controlled trials.

Aim: To verify the effects of physical exercise on low back pain (LBP) and serum cortisol levels in individuals with chronic LBP. Materials & methods: Randomized controlled trials evaluating the effects of exercise on LBP perception and cortisol levels in adults with nonspecific chronic LBP were included. Results: Four randomized controlled trials were included, with a total of 85 participants in the exercise group and 84 in the control group. The interventions reduced -1.61 (95% CI: -2.36 to -0.85) with inconsistency I2 = 72% (p = 0.031) the LBP level and increased 1.05 (95% CI: 0.22-2.32) with inconsistency I2 = 86% (p < 0.0001) the cortisol levels. Conclusion: The practice of physical exercise for 6 weeks or more reduced LBP levels, whereas the rate of progression of an exercise-training program in people with chronic LBP is greater than 4 weeks, but increased the cortisol serum levels in individuals with LBP.