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PURPOSE:To compare the acute physiological responses of low-load resistance exercise (RE) with blood flow restriction (LL-BFR) to traditional high-load RE without BFR (HL-RE) in individuals with multiple sclerosis (MS). METHODS: Fifteen participants (men: n = 4; women: n = 11) with a confirmed diagnosis of relapsing-remitting MS randomly completed the following RE conditions: 1) LL-BFR, consisting of 4 sets (30-15-15-15) of bilateral leg press (LP) and knee extension (KE), at 20% of their 1RM, and with 50% of BFR and 2) HL-RE, consisting of 4 sets (10-10-10-10) of the same exercises at 70% of 1RM without BFR. There was a 1-min rest period between sets and 5 min between exercises. Lactate [La-] was measured at rest, 5 min post-, and 60 min post-exercise; muscle thickness (MT) for the 50% portion of the thigh was measured via ultrasound at rest, immediately post-, 30 min, and 60 min post-exercise; and the myoelectric activity of the vastus medialis (VM) and vastus lateralis (VL) muscles of both legs was measured using superficial electromyography (EMG) during each trial. Repeated measures analyses of variance with Bonferroni post hoc were used to detect significant differences between conditions within each time point. RESULTS: Although both trials significantly (p < 0.001) increased [La-] 5 min post-exercise, HL-RE resulted in significantly greater [La-] compared to LL-BFR (3.72 ± 1.41 vs. 2.20 ± 0.67 mmol/L, p < 0.001), however, both returned to resting levels 60 min post-exercise. There were no significant differences between HL-RE and LL-BFR for MT (cm) at any time point for either the right or left leg (p = 0.64 and p = 0.98). Additionally, MT was significantly (p ≤ 0.03) greater than resting (right: 3.43 ± 0.71, left: 3.43 ± 0.61) immediately post- (3.76 ± 0.68) and 30 min post-exercise (3.58 ± 0.73) for the right leg and immediately post (3.81 ± 0.66) for the left leg. HL-RE induced significantly (p < 0.001) greater EMG values than BFR-RE for the VM and VL muscles of both legs during the LP and KE exercises. CONCLUSIONS: HL-RE seems to induce greater acute physiological responses than BFR-RE for the measured parameters. Nonetheless, BFR-RE was well tolerated by the subjects and elicited significant increases in all the physiological parameters measured, which indicates that it may serve as a potential training strategy for MS patients. [ABSTRACT FROM AUTHOR]

Few data exist identifying the influence of age on midthigh muscle composition. Further understanding how muscle composition of the midthigh changes with aging may improve current exercise prescriptions. PURPOSE: To examine the influence of chronological age on midthigh composition in 142 women (49.1±17.7 years, 164.5±7.1 cm, 66.6±10.7 kg). METHODS: Midthigh peripheral quantitative computed tomography scans were completed at the 40% site of the right femur and were analyzed using BoneJ software. Muscle density (MuD), cross-sectional area (mCSA), and intramuscular fat area (IMAT) were derived from the scans. One-way ANOVA compared group means by decade 20-29 (n=28), 30-39 (n=21), 40-49 (n=22), 50-59 (n=25), 60-69 (n=29), ≥70 years (n=17), while Dunnett's test performed post-hoc pairwise comparisons with the youngest group. Spearman's correlations examined each parameters association with age. A significance level of p<0.05 was selected a priori. RESULTS: MuD and mCSA displayed significant negative associations with age (r=-0.58 and r=-0.67, respectively, both p<0.01), while IMAT displayed a significant positive association with age (r=0.17, p=0.04). Group differences were observed for MuD (p<0.01), mCSA (p<0.01), IMAT (p=0.029). Dunnett's test revealed that MuD was significantly greater in the 20-29 years group compared to both age groups ≥60 years (81.5±1.2mg/cm³ vs 79.1±2.2mg/cm³ and 78.2±2.9mg/cm³, respectively; both p<0.01), and mCSA was significantly greater in the 20-29 years group compared to each age group ≥50 years (104.4±15.4cm² vs 85.9±14.3cm², 78.8±12.4cm², and 72.3±14.5cm², respectively, all p<0.01). IMAT was significantly greater in ≥70 years group compared to the 20-29 years group (6.23±2.3cm² vs 4.3±1.8cm², p=0.04). Interestingly, MuD, a surrogate for muscle quality, displayed smaller age-related decreases than mCSA (MuD: -3.9% vs mCSA: -29.7%) between the 20-29 and ≥70 years group. CONCLUSIONS: The current observations reveal that increased age displayed significant associations with midthigh muscle composition (MuD, mCSA, IMAT). However, future research is needed to identify which muscle composition parameter(s) contribute most effectively to maintaining muscle strength and physical performance with advanced age. [ABSTRACT FROM AUTHOR]