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Low-Load High Volume Resistance Exercise Stimulates Muscle Protein Synthesis More Than High-Load Low Volume Resistance Exercise in Young Men
Background
We aimed to determine the effect of resistance exercise intensity (% 1 repetition maximum—1RM) and volume on muscle protein synthesis, anabolic signaling, and myogenic gene expression.
Methodology/Principal Findings
Fifteen men (21±1 years; BMI = 24.1±0.8 kg/m2) performed 4 sets of unilateral leg extension exercise at different exercise loads and/or volumes: 90% of repetition maximum (1RM) until volitional failure (90FAIL), 30% 1RM work-matched to 90%FAIL (30WM), or 30% 1RM performed until volitional failure (30FAIL). Infusion of [ring-13C6] phenylalanine with biopsies was used to measure rates of mixed (MIX), myofibrillar (MYO), and sarcoplasmic (SARC) protein synthesis at rest, and 4 h and 24 h after exercise. Exercise at 30WM induced a significant increase above rest in MIX (121%) and MYO (87%) protein synthesis at 4 h post-exercise and but at 24 h in the MIX only. The increase in the rate of protein synthesis in MIX and MYO at 4 h post-exercise with 90FAIL and 30FAIL was greater than 30WM, with no difference between these conditions; however, MYO remained elevated (199%) above rest at 24 h only in 30FAIL. There was a significant increase in AktSer473 at 24h in all conditions (P = 0.023) and mTORSer2448 phosphorylation at 4 h post-exercise (P = 0.025). Phosporylation of Erk1/2Tyr202/204, p70S6KThr389, and 4E-BP1Thr37/46 increased significantly (P<0.05) only in the 30FAIL condition at 4 h post-exercise, whereas, 4E-BP1Thr37/46 phosphorylation was greater 24 h after exercise than at rest in both 90FAIL (237%) and 30FAIL (312%) conditions. Pax7 mRNA expression increased at 24 h post-exercise (P = 0.02) regardless of condition. The mRNA expression of MyoD and myogenin were consistently elevated in the 30FAIL condition.
Conclusions/Significance
These results suggest that low-load high volume resistance exercise is more effective in inducing acute muscle anabolism than high-load low volume or work matched resistance exercise modes.
Resistance exercise stimulates the synthesis of skeletal muscle proteins [1], [2], which is eventually expressed as muscle hypertrophy [3], [4]. It is commonly recommended that high-load contractions (i.e., ?70% of 1 repetition maximum; 1RM) be performed to provide an optimal stimulus for muscle growth [5]. It has recently been established, however, that myofibrillar (MYO) protein synthesis is already maximally stimulated at 60% 1RM, in the post-absorptive state, with no further increase at higher load intensities (i.e., 75–90% 1RM) [6]. Additionally, performance of low-load contractions (~20% 1RM) with vascular occlusion is sufficient to induce an increase in mixed muscle (MIX) protein synthesis [7], which explains the significant improvements in muscle size and strength, equivalent to those seen at higher contractile intensities, that occur with blood flow occluded training [8], [9], [10]. Collectively, these data suggest that heavy (i.e., high intensity) external loads are not a prerequisite to elicit increases in muscle protein synthesis [7] and ultimately muscle hypertrophy [8], [9], [10].
PLoS ONE: Low-Load High Volume Resistance Exercise Stimulates Muscle Protein Synthesis More Than High-Load Low Volume Resistance Exercise in Young Men
Background
We aimed to determine the effect of resistance exercise intensity (% 1 repetition maximum—1RM) and volume on muscle protein synthesis, anabolic signaling, and myogenic gene expression.
Methodology/Principal Findings
Fifteen men (21±1 years; BMI = 24.1±0.8 kg/m2) performed 4 sets of unilateral leg extension exercise at different exercise loads and/or volumes: 90% of repetition maximum (1RM) until volitional failure (90FAIL), 30% 1RM work-matched to 90%FAIL (30WM), or 30% 1RM performed until volitional failure (30FAIL). Infusion of [ring-13C6] phenylalanine with biopsies was used to measure rates of mixed (MIX), myofibrillar (MYO), and sarcoplasmic (SARC) protein synthesis at rest, and 4 h and 24 h after exercise. Exercise at 30WM induced a significant increase above rest in MIX (121%) and MYO (87%) protein synthesis at 4 h post-exercise and but at 24 h in the MIX only. The increase in the rate of protein synthesis in MIX and MYO at 4 h post-exercise with 90FAIL and 30FAIL was greater than 30WM, with no difference between these conditions; however, MYO remained elevated (199%) above rest at 24 h only in 30FAIL. There was a significant increase in AktSer473 at 24h in all conditions (P = 0.023) and mTORSer2448 phosphorylation at 4 h post-exercise (P = 0.025). Phosporylation of Erk1/2Tyr202/204, p70S6KThr389, and 4E-BP1Thr37/46 increased significantly (P<0.05) only in the 30FAIL condition at 4 h post-exercise, whereas, 4E-BP1Thr37/46 phosphorylation was greater 24 h after exercise than at rest in both 90FAIL (237%) and 30FAIL (312%) conditions. Pax7 mRNA expression increased at 24 h post-exercise (P = 0.02) regardless of condition. The mRNA expression of MyoD and myogenin were consistently elevated in the 30FAIL condition.
Conclusions/Significance
These results suggest that low-load high volume resistance exercise is more effective in inducing acute muscle anabolism than high-load low volume or work matched resistance exercise modes.
Resistance exercise stimulates the synthesis of skeletal muscle proteins [1], [2], which is eventually expressed as muscle hypertrophy [3], [4]. It is commonly recommended that high-load contractions (i.e., ?70% of 1 repetition maximum; 1RM) be performed to provide an optimal stimulus for muscle growth [5]. It has recently been established, however, that myofibrillar (MYO) protein synthesis is already maximally stimulated at 60% 1RM, in the post-absorptive state, with no further increase at higher load intensities (i.e., 75–90% 1RM) [6]. Additionally, performance of low-load contractions (~20% 1RM) with vascular occlusion is sufficient to induce an increase in mixed muscle (MIX) protein synthesis [7], which explains the significant improvements in muscle size and strength, equivalent to those seen at higher contractile intensities, that occur with blood flow occluded training [8], [9], [10]. Collectively, these data suggest that heavy (i.e., high intensity) external loads are not a prerequisite to elicit increases in muscle protein synthesis [7] and ultimately muscle hypertrophy [8], [9], [10].
PLoS ONE: Low-Load High Volume Resistance Exercise Stimulates Muscle Protein Synthesis More Than High-Load Low Volume Resistance Exercise in Young Men
