Follow Us on Facebook      Subscribe to us on YouTube

Follow Us on Twitter      IronMagLabs on Instagram

April 2014
S M T W T F S
« Mar    
 12345
6789101112
13141516171819
20212223242526
27282930  







































IronMagLabs - Bodybuilding Supplements

Yesterday we wrote that strength athletes build up more lean body mass if they consume whey rather than soya protein or fast carbohydrates just after a training session. Earlier this year the authors of that study published the results of another study in which pre-training whey supplementation inhibited the increase in the stress hormone cortisol, and supplementation with soya protein or carbohydrates did not.

Yesterday we wrote that strength athletes build up more lean body mass if they consume whey rather than soya protein or fast carbohydrates just after a training session. Earlier this year the authors of that study published the results of another study in which pre-training whey supplementation inhibited the increase in the stress hormone cortisol, and supplementation with soya protein or carbohydrates did not.

Cortisol is a useful, even essential hormone, but strength athletes who want to build up muscle mass would prefer to keep their post-workout levels down. Cortisol forces muscles to convert proteins into energy and also inhibits the effect of the androgen receptor, through which muscle cells receive important anabolic signals.

Researchers have long known that intensive exertion causes cortisol levels to rise, and that combining quickly absorbed nutrients such as simple carbohydrates with a high glycaemic index helps to reduce the rise. In the study we’re referring to here, the researchers wanted to find out whether fast-absorbed proteins also have this effect.

The researchers got ten experienced young strength athletes to do six sets of squats using a weight that they could just manage ten reps with, on three different occasions. One time the men drank a shake containing 20 g of the easily absorbed carbohydrate maltodextrin [CHO], another time they drank a shake containing 19 g whey isolate [WPI], and the third time they drank a shake containing 18 g soya-protein isolate [SPI]. The athletes drank the shakes twenty minutes before starting their workout. The soya-protein shake also contained 26 mg isoflavones.

The figure below shows how the cortisol level in the men’s blood rose after doing strength training. When the men had drunk the whey shake the increase was noticeably less than after drinking the soya-protein or maltodextrin shake.

1

2

The researchers also noticed that there was an effect on the men’s testosterone level. This rose more after the men had drunk the whey shake than after the soya-protein shake. The effect is less impressive than the effect on the cortisol level however.

The researchers interpret both the hormonal effects of whey as being positive, and suspect that strength athletes can recover faster from strength training by consuming a portion of whey just before a session.

The effects of soy and whey protein supplementation on acute hormonal reponses to resistance exercise in men.

Kraemer WJ, Solomon-Hill G, Volk BM, Kupchak BR, Looney DP, Dunn-Lewis C, Comstock BA, Szivak TK, Hooper DR, Flanagan SD, Maresh CM, Volek JS.

Abstract

OBJECTIVE:

For many resistance-trained men concerns exist regarding the production of estrogen with the consumption of soy protein when training for muscle strength and size. Thus, the purpose of this investigation was to examine the effects of soy and whey protein supplementation on sex hormones following an acute bout of heavy resistance exercise in resistance trained men.

METHODS:

Ten resistance-trained men (age 21.7 ± 2.8 [SD] years; height 175.0 ± 5.4 cm; weight 84.2 ± 9.1 kg) volunteered to participate in an investigation. Utilizing a within subject randomized crossover balanced placebo design, all subjects completed 3 experimental treatment conditions supplementing with whey protein isolate (WPI), soy protein isolate (SPI), and maltodextrin placebo control for 14 days with participants ingesting 20 g of their assigned supplement each morning at approximately the same time each day. Following supplementation, subjects performed an acute heavy resistance exercise test consisting of 6 sets of 10 repetitions in the squat exercise at 80% of the subject’s one repetition maximum.

RESULTS:

This investigation observed lower testosterone responses following supplementation with soy protein in addition to a positive blunted cortisol response with the use of whey protein at some recovery time points. Although sex hormone binding globulin (SHBG) was proposed as a possible mechanism for understanding changes in androgen content, SHBG did not differ between experimental treatments. Importantly, there were no significant differences between groups in changes in estradiol concentrations.

CONCLUSION:

Our main findings demonstrate that 14 days of supplementation with soy protein does appear to partially blunt serum testosterone. In addition, whey influences the response of cortisol following an acute bout of resistance exercise by blunting its increase during recovery. Protein supplementation alters the physiological responses to a commonly used exercise modality with some differences due to the type of protein utilized.

PMID: 24015701 [PubMed - in process]

Source: http://www.ncbi.nlm.nih.gov/pubmed/24015701

Comments

comments