Keep Protein Intake High For Enhanced IGF-I Responses

            Inadequate protein or energy may be a factor that contributes to a decline in circulating IGF-I during intense training. Protein intake has direct effect on raising IGF-I levels.  One study examined the effect of different protein intakes on the regulation of serum IGF-I.  Subjects were fasted for 5 days which lead to a huge drop in serum IGF-I levels and were refed three diets of different composition (a normal diet, a low-protein normal energy diet, and a low protein, low energy diet) in the 5 postfast days.  Refeeding a normal diet (35kcal/kg/day containing 1.35 g protein/kg/day) raised IGF-I

to nearly 70% to prefast values by the fifth day, while refeeding a protein-deficient isocaloric diet (0.43 g/kg/ day) resulted in a 2-day delay in the upward rise of IGF-I and increased IGF-I to only 50% of control prefast values¹⁵. Consuming high protein is essential during any heavy training program.  No, a fig-newton is not going to cut it to preserve IGF-I levels!! You need to be consuming some type of protein based supplementation.  For example, one study examined IGF-I levels in response to six months of resistance exercise.  Total calories were the same between the groups except one group was assigned to a protein supplementation group (2.2 g per kg of bodyweight) and the other a high carbohydrate with moderate protein (1.0 g per kg of bodyweight).  The results of the study found that the group consuming protein supplementation had greater increases in plasma concentrations of IGF-I compared to subjects consuming a carbohydrate supplement¹¹.  Additionally, Kraemer et al. reported that young men who consumed Mass Fuel two hours before their workout and one-immediate post-exercise had higher IGF-1 levels after exercise on days 2 and 3 post-exercise¹⁴. Essential Amino Acids (primarily Branched Chain Amino Acids) have been shown to impact serum IGF-I and nitrogen balance to a greater extent than do nonessential amino acids¹⁵. One study examined IGF-I and fatigue levels in competitive rugby players before a national tournament.  Interestingly, all the rugby players had a decline in circulating IGF-I levels after the match that was lower than adult norms.  When energy intake was examined, the total calorie intake was 6% lower than what the were supposed to be consuming and mean protein intake was 1.27 g per kg of bodyweight while recommended protein intake for rugby players is 1.5-2 g per kg of bodyweight.  Thus high intensity exercise in conjunction with insufficient calories and protein could have led to the drop in IGF-I levels. 

Use Forced Reps, Drop Sets, and Negatives...Occasionally

           Training to failure does have its place in your training regimen; you just can't do it every set.  Going to failure or using forced reps is kind of like going out with the boys to the bars to drink, its ok once in a while but doing it every night will leave you looking like a Skinny Kid Rock!  Although many bodybuilders may think you have to "shock" your body into growth with high intensity exercises such as training to muscle failure or using forced reps is key to muscle growth...to the authors knowledge no research study has ever proven that training to failure is necessary to muscle growth. No bodybuilder gets "big" overnight.  The science of increasing muscle mass is similar to trying to get a darker tan. You gradually expose your skin to the sun and your tan darkens, it is not necessary to subject your skin to the most intense sunlight it can withstand up to the moment before blistering. Muscle growth stimulation operates on the same principle. Consequently it is not necessary to operate a muscle to its absolute limit of muscular failure in order to stimulate new muscle growth. The use of forced reps is a tool that can be thrown into your training arsenal but recuperating from forced reps is taxing on the body.  One study examined anabolic hormone response over a 3 day period in lifters using 2 types of popular bodybuilding protocols: one trained to maximal exhaustion and the other used forced reps.  The total training volume was the same for both groups except the forced reps subjects had spotters assist them for the last 3-5 reps.  Immediately post-exercise, there was no difference in testosterone production between the groups but the forced reps group had a higher GH response but also a higher cortisol response.  Additionally, the group performing forced reps had a greater decrease in maximal isometric force compared to the maximal resistance group¹⁸.  So the use of forced reps is a double edged sword, on one hand you get higher GH responses, but on the other hand you also produce higher cortisol and have reduced muscle strength with may lead to overtraining.  The ability of your muscle to contract is controlled by your central nervous system. As your nervous system controls your muscles through electrical impulses, overtrained or recently trained muscles require a larger signal to actually complete a contraction of the same magnitude as a rested muscle. By training intuitively you can still cause sufficient microtrauma to your muscles fibers to encourage growth, without continually draining your nervous system. Training to just before failure will still create gains.

Multiple Sets are Better for Strength and Hormone Responses

So you may be thinking may be I should cut back on my sets and adopt a HIT type training with 1 high intensity and not train to failure to maximize training recuperation.  Heavy duty training dismisses the possibility of significant muscular growth arising from anything other than brief, infrequent, maximal exertions. In practice however, most successful bodybuilders develop their physiques doing almost exactly the opposite. One study examined IGF-I and IGFBP-3 over a 25 week with subjects performing either 1 set or 3 sets of resistance exercise.  Both groups had a 20% increase IGF-I at week 13, but after week 13 the 3 set group had larger increases in strength that occurred with a drop in IGFBP-3 (decreased 20%).  Additionally, the 3 sets group had an approximately 50% greater increase in strength compared to the 1 set group⁷.