The effect of exercise on growth hormone (GH) secretion and subsequent impact on muscle gains, is not well understood. However, sports scientists do know that intense (heavy) weight training produces a significant increase in bio-active GH levels. Also, bodybuilders seem to possess higher resting GH levels than their sedentary counterparts.
However, recent studies performed at Bill Kraemer’s lab reinforce an important fundamental aspect that is often overlooked by bodybuilders in their quest for lean muscle mass.
Dr Kraemer's research showed that heavy deadlifts and squats should never be neglected if you’re after the best results from your training. This research showed that a workout program that incorporated these heavy compound lifts was responsible for producing much higher GH levels.
In this study, two groups of collegiate athletes were placed on two different strength training programs for 6 months. The first group followed a progressive overload program using heavy resistance (1-8 max rep range) and exercises that worked the entire body. The second group followed the exact same program but without the key exercises squats and deadlifts.
Often, GH readings vary among assessment techniques. Results from this study are pertinent, as three different GH assessment methods were used. Total concentration of GH in unfractioned plasma was measured by the Nichols immunoradiometric assay (NLS), NIDDK polyclonal competitive RIA (NIDDK); and the rat tibial bioassay (RTL) —these are all quality GH analyses.
NLS results showed that while both training groups demonstrated an increase in GH levels after exercise, the GH response in the group that performed squats and deadlifts was significantly higher than the group that followed the upper body program.
For the NIDDK assay, again both training groups showed an increase in post-exercise GH levels. However, once again, GH values were higher in the group that incorporated heavy leg work into their program. The RTL assay revealed that the total body training resulted in a higher pre to post-exercise boost in GH as compared to upper body-only training. Additionally, body composition assessments (by DEXA) revealed that this group also gained more muscle throughout their entire body.
The data obtained clearly demonstrate that exercise selection during training produce a markedly different GH response. Additionally, the amount of muscle mass trained appears to influence GH secretion. Barbell squats and dead lifts use the largest muscle groups and these exercises appear to be responsible for significantly greater increases in GH production during resistance training.
Simple exercise selection does have an effect on growth hormone release, muscle growth and athletic performance. Squats and deadlifts dramatically impact natural growth hormone release and in turn, positively impact lean muscle growth.
Source: NSCA Annual National Conference in Indianapolis, IN.