Sex Differences and Physical Activity Status on the Hamstring: Quadriceps Ratio, Activities of Daily Living, and Functional Movement in Older Adults

International Journal of Exercise Science 16(4): 1228-1243, 2023. The study aimed to investigate sex differences and the effect of physical activity on the hamstring:quadriceps (H:Q) ratio, activities of daily living (ADLs), and the Functional Movement Screen (FMS) in older adults. Thirty older adults (72.56 + 6.22) completed maximal voluntary isometric contractions (MVICs), ADLs, the FMS, and three closed-kinetic chain exercises (CKCs); front lunge (FL), side lunge (SL), and bilateral squat (BLSQ). Electromyography was recorded from the biceps femoris (BF) and vastus lateralis (VL) on the dominant and non-dominant limbs during the MVICs and CKCs. Raw EMG recordings were normalized to MVICs and analyzed for root mean square (RMS). The H:Q ratio was calculated using RMS as BF/VL. It was determined that males had significantly higher H:Q ratios during the FL (p = 0.002), SL (p = 0.012) and BLSQ (p = 0.023), as well as higher RMS of the BF during the FL (p = 0.031), SL (p = 0.01), and BLSQ (p = 0.042). Females scored higher on the ADLs and FMS. A significant positive correlation was observed between ADLs and RMS of the VL (p \u3c 0.05, r \u3e 0.40), whereas a negative correlation was observed between ADLs and RMS of the BF (p \u3c 0.05, r \u3c -0.5). The results suggest that males may activate their hamstrings more effectively than females and that females may tend to remain quadriceps dominant. High motor unit recruitment of the hamstring muscles may coincide with reduced functional ability, whereas high motor unit recruitment of the quadriceps may coincide with enhanced functional ability

Age-related differences in maximal and rapid hamstrings to quadriceps strength capacities and vertical jump power

BACKGROUND AND AIMS: Declines in hamstrings and quadriceps maximal and rapid strength are commonly reported as a consequence of aging; however, few studies have investigated the influence of age on maximal and rapid hamstrings to quadriceps (H/Q) strength ratios. This study aimed to examine the effects of age on leg extension and flexion maximal and rapid torque production, H/Q strength ratios, and muscle power in healthy, young and old females. METHODS: Fifteen young (21 ± 2 years) and 15 old (69 ± 7 years) females performed 3 isometric leg extension and flexion maximal voluntary contractions (MVCs), from which peak torque (PT), early (0-30 ms) and late (0-200 ms) phase rate of torque development (RTD), and PT and RTD H/Q strength ratios were extracted. Lower-body peak power output (P max) was assessed through a vertical jump test. RESULTS: P max, PT, and early (RTD30) and late (RTD200) RTD variables of the leg extensors and flexors were lower (P ≤ 0.048) and PT and RTD200 H/Q strength ratios were higher (P ≤ 0.030) in the old compared to the younger females; however, no difference was observed for RTD30 H/Q (P = 0.300). There were also significant negative relationships in the older (r = -0.616 and -0.522; P = 0.014 and 0.046) but not the younger (r = 0.295 and -0.109; P = 0.286 and 0.698) females between P max and RTD30 and RTD200 H/Q strength ratios. CONCLUSION: The higher RTD200 H/Q ratio for the older females may contribute to the muscle power deficits often observed in elderly populations. Practitioners may use these findings to help identify older adults with low muscle power capacities and possibly overall functional decline

Age-related effects on maximal and rapid hamstrings/quadriceps strength capacities and vertical jump power in young and older females

Background and aims Declines in hamstrings and quadriceps maximal and rapid strength are commonly reported as a consequence of aging; however, few studies have investigated the influence of age on maximal and rapid hamstrings to quadriceps (H/Q) strength ratios. This study aimed to examine the effects of age on leg extension and flexion maximal and rapid torque production, H/Q strength ratios, and muscle power in healthy, young and old females. Methods Fifteen young (21 ± 2 years) and 15 old (69 ± 7 years) females performed 3 isometric leg extension and flexion maximal voluntary contractions (MVCs), from which peak torque (PT), early (0–30 ms) and late (0–200 ms) phase rate of torque development (RTD), and PT and RTD H/Q strength ratios were extracted. Lower-body peak power output (Pmax) was assessed through a vertical jump test. Results Pmax, PT, and early (RTD30) and late (RTD200) RTD variables of the leg extensors and flexors were lower (P ≤ 0.048) and PT and RTD200 H/Q strength ratios were higher (P ≤ 0.030) in the old compared to the younger females; however, no difference was observed for RTD30 H/Q (P = 0.300). There were also significant negative relationships in the older (r = −0.616 and −0.522; P = 0.014 and 0.046) but not the younger (r = 0.295 and −0.109; P = 0.286 and 0.698) females between Pmax and RTD30 and RTD200 H/Q strength ratios. Conclusion The higher RTD200 H/Q ratio for the older females may contribute to the muscle power deficits often observed in elderly populations. Practitioners may use these findings to help identify older adults with low muscle power capacities and possibly overall functional decline