Toshiharu Natsume

Effects of Electrostimulation with Blood Flow Restriction on Muscle Size and Strength

PURPOSE Low-load voluntary exercise can induce muscle hypertrophy and strength gain in working muscles when combined with blood flow restriction (BFR). However, it is unknown whether such hypertrophy and strength gain can be induced by involuntary muscle contractions triggered via low-intensity neuromuscular electrical stimulation (NMES) combined with BFR. The purpose of this article was to investigate whether low-intensity NMES combined with BFR (NMES-BFR) could elicit muscle hypertrophy and strength gain in the quadriceps. METHODS Eight untrained young male participants (mean ± SE; age, 26.2 ± 0.7 yr; height, 1.74 ± 0.02 m; body weight, 71.4 ± 4.8 kg) were subjected to 23 min of unilateral low-intensity (5%-10% of maximal voluntary contraction) NMES twice per day (5 d·wk⁻¹) for 2 wk: one leg received NMES-BFR and the other leg received NMES alone. Quadriceps muscle thickness and isometric and isokinetic strength were measured before and every week throughout the training and detraining periods. RESULTS In NMES-BFR legs, muscle thickness increased after 2 wk of training (+3.9%) and decreased after 2 wk of detraining (-3.0%). NMES-BFR training also increased maximal knee extension strength in isometric (+14.2%) and isokinetic (+7.0% at 90°·s⁻¹ and +8.3% at 180°·s⁻¹) voluntary contractions. In addition, maximal isometric strength decreased (-6.8%), whereas no large fall (-1.9% at 90°·s⁻¹ and -0.6% at 180°·s⁻¹) in isokinetic maximal strength was evident after 2 wk of detraining. In legs that received NMES alone, no prominent change was observed; there was a negligible effect on isometric strength. CONCLUSION Low-intensity NMES-BFR induces muscle hypertrophy and strength gain in untrained young male participants.

Effects of drop sets with resistance training on increases in muscle CSA, strength, and endurance: a pilot study

ABSTRACT To investigate the effects of a single high-load (80% of one repetition maximum [1RM]) set with additional drop sets descending to a low-load (30% 1RM) without recovery intervals on muscle strength, endurance, and size in untrained young men. Nine untrained young men performed dumbbell curls to concentric failure 2–3 days per week for 8 weeks. Each arm was randomly assigned to one of the following three conditions: 3 sets of high-load (HL, 80% 1RM) resistance exercise, 3 sets of low-load [LL, 30% 1RM] resistance exercise, and a single high-load (SDS) set with additional drop sets descending to a low-load. The mean training time per session, including recovery intervals, was lowest in the SDS condition. Elbow flexor muscle cross-sectional area (CSA) increased similarly in all three conditions. Maximum isometric and 1RM strength of the elbow flexors increased from pre to post only in the HL and SDS conditions. Muscular endurance measured by maximum repetitions at 30% 1RM increased only in the LL and SDS conditions. A SDS resistance training program can simultaneously increase muscle CSA, strength, and endurance in untrained young men, even with lower training time compared to typical resistance exercise protocols using only high- or low-loads.

Effects of a progressive walking program on the risk of developing locomotive syndrome in elderly Japanese people: a single-arm trial

[Purpose] This study aimed to identify the efficacy of a progressive walking program on the risk of developing locomotive syndrome among untrained elderly Japanese people. [Participants and Methods] Twenty-four untrained elderly individuals (68 ± 4 years) completed a 17-week progressive walking program. The stand-up, two-step tests and the 25-question geriatric locomotive function scale were used to assess the risk of locomotive syndrome at baseline, the 8-week midpoint (2 months), and the 17-week endpoint (4 months). Maximal isometric muscle strength of the knee extensors and flexors were measured using a dynamometer with the hip joint angle at 90° of flexion and physical function (the 30-s sit-to-stand, sit-up, 10-meter walk, and grip strength) were evaluated. [Results] The 4-month walking program significantly improved the two-step test and geriatric locomotive function scale scores. This may be attributable to the improvement in knee flexor strength and physical function. [Conclusion] A 4-month program of progressive walking effectively lowered the risk of developing locomotive syndrome in elderly Japanese people by improving knee flexor muscle strength and physical function.

Passive Muscle Movements Combined With Blood Flow Restriction Can Induce Muscle Hypertrophy: 1709 Board #362 June 2, 9: 00 AM - 10: 30 AM.

BACKGROUND: According to the Standard Canadian Society of Exercise Physiology (SCSEP), individuals <45 yr are to complete the partial curl-up test at a reach distance of 12 cm. PURPOSE: This study aimed to investigate the effect of spinal flexibility, arm length, height, and torso length on execution of the SCSEP curl-up test, as factors not previously studied according to the knowledge of the researchers, and in addition to previously studied variables of age, waist circumference, plank time and reported physical activity. To the best of our knowledge, no study has assessed all of these variables at varying reach distances of 8, 10, and 12 cm. METHODS: Maximal plank time and anatomical assessments were recorded for 45 [age 22 (18-36)] subjects. Each subject completed a partial curl-up test following the SCSEP protocol as defined in the ACSM’s Guidelines for Exercise Testing and Prescription, Ninth Edition, at reach distances of 8, 10, and 12 cm in randomized order and 2448 hours apart. A one-way MANOVA was calculated examining the effect of individual characteristics on performance of the three curl-up tests. RESULTS: A significant effect was found for age (Lambda (30, 94.6) = .252, p<.05) on execution of the curl-up test [Lambda (99, 27.8) = .001, p<.05]. Follow-up univariate ANOVAs indicated that execution of the curl-up test at 10cm and 12cm were significantly diminished ([F(10, 34) = 3.063, p < .05], [F(10,34) = 3.348, p<.05], respectively). Execution of the curl-up test was not significantly affected by spinal flexibility, arm length, torso length, waist circumference, maximal plank hold time, and reported physical activity. CONCLUSION: The decline in execution of the curl-up test with increasing age has been reported previously, however, it appears age may impact performance earlier than 45 yrs, warranting further research examining smaller age increments and their effect on curl-up execution. In subjects <45 yr, spinal flexibility, arm length, and torso length do not appear to impact execution of the curl-up test at any of the reach distances examined.