I love asking the top pros questions and one of the common questions is, “What supplements do you take while you are dieting for a show?” All of them take multivitamins and many of the top bodybuilders who are sponsored by MD have one thing in common— they all take branched-chain amino acids (BCAAs) during the weeks leading up into a show.
All of the pros I’ve interviewed said that during times of calorie restriction, they feel the use of BCAAs reduces muscle tissue breakdown and keeps them in an anabolic state. There was an interesting paper just published in the Acta Physiologica that sheds some light on why taking BCAAs during the dieting phase before a show may create a more anabolic state, and result in less muscle breakdown. There is an interesting protein called p70S6k. In recent years, marked progress has been made in identifying the signaling substrates essential for muscle growth and development. mTOR is stimulated by the amino acid leucine; another key signaling protein for muscle hypertrophy is p70S6k. Persistent overexpression of IGF-1 in skeletal muscle of mice results in hypertrophy, which is mediated via the mTOR/ p70S6k pathway.
Another interesting fact is that muscle hypertrophy seems to be blunted in aged humans, and one of the reasons may be that mTOR and p70S6k are blunted in skeletal muscle in aged animals after a single bout of intense contractile activity. These observations suggest that the anabolic response of both mTOR and p70S6k to a single bout of contraction is attenuated by aging, and may help explain the reduced capacity for hypertrophy in older people.
p70S6k Correlates With Increased Muscle Mass
The anabolic benefits of resistance exercise are likely to be mediated through changes in signal transduction proteins. One of the key anabolic-regulating proteins is p70S6k. This protein has emerged as an important factor in muscle cell size regulation, as it is a regulator of the mTOR pathway— known to regulate muscle growth. p70S6k is an important activator of the insulin/IGF-1 pathway. Animal studies have reported that castration and a subsequent decline in testosterone leads to a rapid decrease in p70S6k and muscle atrophy. However, administration of testosterone induces a rapid increase in p70S6k and upregulation of IGF-1.
Interestingly, the muscle hypertrophy induced by clenbuterol was associated with local increases in IGF-1 and p70S6k in muscle. Exercise-induced increases in p70S6k activity correlate with increased muscle mass after six weeks of resistance exercise, and with elevated protein synthesis rates in muscle, both 12 and 24 hours into recovery. Based on the research, an increase in p70S6k activity increases protein synthesis and correlates with increased muscle mass.
BCAAs Increase p70S6k at Rest and During Exercise
Researchers from the Swedish School of Sport and Health Sciences examined the role of BCAAs before exercise. Subjects were randomly supplied either a mixture of BCAAs or flavored water. Muscle biopsies were taken from both resting and exercising muscle before, after and one hour after exercise. p70S6k was unaffected by resistance exercise alone; however, BCAA intake increased phosphorylation in both legs following exercise.
A novel finding is that BCAAs enhance p70s6k activity in both resting and exercising muscle. Thus, BCAAs and resistance exercise have a synergistic effect on increasing p70S6k but what is unique about the above study is that BCAAs led to an increase in p70S6k activity after exercise— which was not reported before. This should be a reason for bodybuilders to take BCAAs during the competitive phase before a show, as they stimulate key pathways for muscle growth and anabolic activity.
All of the pros I’ve interviewed said that during times of calorie restriction, they feel the use of BCAAs reduces muscle tissue breakdown and keeps them in an anabolic state. There was an interesting paper just published in the Acta Physiologica that sheds some light on why taking BCAAs during the dieting phase before a show may create a more anabolic state, and result in less muscle breakdown. There is an interesting protein called p70S6k. In recent years, marked progress has been made in identifying the signaling substrates essential for muscle growth and development. mTOR is stimulated by the amino acid leucine; another key signaling protein for muscle hypertrophy is p70S6k. Persistent overexpression of IGF-1 in skeletal muscle of mice results in hypertrophy, which is mediated via the mTOR/ p70S6k pathway.
Another interesting fact is that muscle hypertrophy seems to be blunted in aged humans, and one of the reasons may be that mTOR and p70S6k are blunted in skeletal muscle in aged animals after a single bout of intense contractile activity. These observations suggest that the anabolic response of both mTOR and p70S6k to a single bout of contraction is attenuated by aging, and may help explain the reduced capacity for hypertrophy in older people.
p70S6k Correlates With Increased Muscle Mass
The anabolic benefits of resistance exercise are likely to be mediated through changes in signal transduction proteins. One of the key anabolic-regulating proteins is p70S6k. This protein has emerged as an important factor in muscle cell size regulation, as it is a regulator of the mTOR pathway— known to regulate muscle growth. p70S6k is an important activator of the insulin/IGF-1 pathway. Animal studies have reported that castration and a subsequent decline in testosterone leads to a rapid decrease in p70S6k and muscle atrophy. However, administration of testosterone induces a rapid increase in p70S6k and upregulation of IGF-1.
Interestingly, the muscle hypertrophy induced by clenbuterol was associated with local increases in IGF-1 and p70S6k in muscle. Exercise-induced increases in p70S6k activity correlate with increased muscle mass after six weeks of resistance exercise, and with elevated protein synthesis rates in muscle, both 12 and 24 hours into recovery. Based on the research, an increase in p70S6k activity increases protein synthesis and correlates with increased muscle mass.
BCAAs Increase p70S6k at Rest and During Exercise
Researchers from the Swedish School of Sport and Health Sciences examined the role of BCAAs before exercise. Subjects were randomly supplied either a mixture of BCAAs or flavored water. Muscle biopsies were taken from both resting and exercising muscle before, after and one hour after exercise. p70S6k was unaffected by resistance exercise alone; however, BCAA intake increased phosphorylation in both legs following exercise.
A novel finding is that BCAAs enhance p70s6k activity in both resting and exercising muscle. Thus, BCAAs and resistance exercise have a synergistic effect on increasing p70S6k but what is unique about the above study is that BCAAs led to an increase in p70S6k activity after exercise— which was not reported before. This should be a reason for bodybuilders to take BCAAs during the competitive phase before a show, as they stimulate key pathways for muscle growth and anabolic activity.
