Electromyography Comparison of Sex Differences During the Back Squat.

ABSTRACT: Mehls, K, Grubbs, B, Jin, Y, and Coons, J. Electromyography comparison of sex differences during the back squat. J Strength Cond Res 36(2): 310-313, 2022-Currently, there is limited information regarding the muscle activity differences between men and women during the traditional back squat. The back squat is a widely used exercise which stimulates lower-body musculature; thus, information regarding the muscle activity patterns during this exercise is pertinent when prescribing resistance training. This study evaluated muscle activity differences (using surface electromyography) in men and women during the traditional back squat with a load prescribed to elicit strength gains. Resistance-trained men (n = 14) and women (n = 14) performed 3 sets of 4 repetitions in the traditional back squat using 85% of their pretest 1 repetition maximum. Muscle activity data were collected for 6 muscles including the vastus lateralis, vastus medialis, rectus femoris, gluteus maximus, semitendinosus, and biceps femoris (BF). Independent sample t tests revealed a significantly higher normalized muscle activity in men in the BF muscle during the descending phase of the back squat. No other muscle activity differences were present between men and women. These results indicate that men activate the BF muscle during the traditional back squat to a greater extent than women. For women, it may be necessary to consider other exercises to optimally stimulate and strengthen the BF muscle during resistance training.

Attenuated aortic blood pressure responses to metaboreflex activation in older adults with dynapenia.

BACKGROUND: Low muscle strength (dynapenia) is a primary characteristic of sarcopenia, the age-related loss of muscle mass and strength or low walking speed. New evidence suggests that muscle strength positively affects blood pressure (BP) responses to exercise. As older adults with lowest handgrip strength also have lowest BP at rest, those with dynapenia may experience attenuated BP responses during physical activity. The purpose of this study was to test the hypothesis that dynapenic older adults would exhibit lower BP response to post-exercise muscle ischemia (PEMI). METHODS: Brachial and aortic systolic BP (SBP), diastolic BP (DBP), and mean arterial pressure (MAP) were measured in older adults (age, 80 ± 5 y) with dynapenia (n = 16) and non-dynapenia (n = 9) at rest and during PEMI following 2 min of isometric handgrip exercise at 30% maximal voluntary contraction. Walking speed was assessed by an 8-foot (2.44 m) walk course. RESULTS: Increases in aortic SBP (11 ± 2 vs. 23 ± 6 mm Hg, p = .03), DBP (6 ± 2 vs.14 ± 4 mm Hg, p = .04), and MAP (8 ± 1 vs. 17 ± 5 mm Hg, p = .02) were lower in dynapenic compared to non-dynapenic adults. Aortic MAP (r = 0.52, p < .05) response to PEMI was correlated with MVC in dynapenic adults. Gait speed was correlated with aortic DBP response to PEMI (r = 0.698, p = .05) in non-dynapenic adults. CONCLUSIONS: Our findings indicate that aortic DBP response to muscle metaboreflex activation is attenuated in older adults with dynapenia. Normal aortic DBP response during metaboreflex activation may positively affect walking performance in non-dynapenic older adults.

Whole-body Vibration Training in Frail, Skilled Nursing Home Residents.

Frailty is a geriatric syndrome characterized by diminished muscle strength, endurance, and weakened physical function. Physical frailty is often unaddressed clinically as it tends to manifest among chronic illnesses and sarcopenia, and consensus criteria for frailty diagnosis remains elusive. Whole-body vibration training (WBVT) has been used to improve deficits in lower body muscular strength and functional performance in healthy and high functioning older adults; therefore, the purpose of this study was to determine the effects of WBVT on physical frailty in skilled nursing home residents. This study compared the effects of 12 wks (2x/wk) of WBVT (n = 10) to standard care, which served as the control (CON: n = 10), on isometric knee extension strength (KE), body composition, and functional performance in 20 (16 female) pre-frail and frail skilled nursing home residents (82 ± 5 yrs). Frailty was assessed using the FRAIL scale and function was measured using the short physical performance battery (SPPB). WBVT consisted of 4 lower body exercises (partial squat, narrow squat, wide squat, calf raise) during vertical vibration (25 - 40 Hz). Data were analyzed using two-way ANOVA (group × time) and post-hoc paired and independent t-tests. Significance was set at p ≤ 0.05. There were significant group-by-time interactions for KE and SPPB. Post-hoc paired t-tests revealed that WBVT improved KE (22.3 ± 4.0 to 29.0 ± 4.5 kg) and improvement in SPPB performance approached significance (4.5 ± 2.3 to 5.2 ± 2.1 units, p = 0.089). WBVT was well tolerated and occurred without adverse health complications. WBVT can be used to counteract losses in leg strength without adverse health complications in skilled nursing home residents.

Effects of green tea extract supplementation and endurance training on irisin, pro-inflammatory cytokines, and adiponectin concentrations in overweight middle-aged men.

PURPOSE: Green tea extract (GTE) supplementation has been proposed to possess anti-inflammatory properties. This study assessed the effects of GTE on endurance training (ET) induced changes on irisin, pro-inflammatory cytokines, adiponectin and anthropometric indices in overweight middle-aged males. METHODS: Participants were randomly assigned to three groups (n = 15): endurance training + placebo (ET + P), endurance training + green tea extract supplementation (ET + GTE), and no endurance training + placebo (P). The ET intervention consisted of an 8-week training program that included circuit training, fast walking or jogging performed three times/week at a moderate intensity (40-59% of the heart rate reserve). Participants received 500 mg/day GTE using a green tea capsule. Serum concentrations of interleukin 6 (IL-6), tumor necrosis factor-alpha (TNF-α), irisin, adiponectin, and high-sensitivity C-reactive protein (hs-CRP) were measured prior to and after the 8-week training intervention. RESULTS: Both exercise interventions decreased IL-6 and hs-CRP (p < 0.05), and increased adiponectin (p < 0.01) levels; changes in these variables were greater in the ET + GTE group compared to the ET + P and P groups (p < 0.01). Irisin concentrations increased only in the ET + GTE group and were different from the ET + P and P groups (p < 0.01). There were no changes in TNF-α concentrations in any of the groups. Both exercise interventions (ET + GTE and ET + P) decreased bodyweight, body mass index (BMI), body fat percentage (BFP), and visceral fat area (VFA) (p < 0.05), with greater changes in these variables occurring in the ET + GTE group compared to ET + P and P groups (p < 0.01). CONCLUSION: The combination of GTE supplementation and ET produces beneficial anti-inflammatory and metabolic effects, which were greater than those produced by ET alone.

A Pilot Study to Assess the Feasibility of Group Exercise and Animal-Assisted Therapy in Older Adults.

This pilot study assessed the feasibility of incorporating animal-assisted therapy teams (ATT) into a 6-week group exercise program for older adults (77 ± 6 years). Fifteen participants were randomly assigned to an exercise with ATT (E+ATT; n = 8) or exercise only (E; n = 7) group. Groups exercised 3x/week for 45 min. Feasibility was assessed by three objectives: (1) ATT will not need extensive preparation beyond their original therapy training; (2) the study will require minimal cost; and (3) ATT must not impair the effectiveness of the exercise program. By the study conclusion, all objectives were met. Time and cost were minimal for ATT, and adherence was 93% and 90% for E+ATT and E, respectively. There were significant improvements in both groups (p ≤ .05) for arm curls, get-up and go, and 6-min walk. The results of this pilot study suggest that it is feasible to incorporate ATT into group exercise programming for older adults.