It has been known that local accumulation of metabolic subproducts such as lactate and hydrogen ions stimulates sympathetic nerve activity and exercise-induced catecholamine (adrenaline) secretion.1 The increase in metabolic stress with increased lactate and adrenaline has recently been shown to play an important role in the regulation of anabolic hormone secretions from the hypothalamus-pituitary.2,3
Therefore, increasing the metabolic stress (lactate) may be an additional stimulatory mechanism for muscle growth. For example, Gordon et al.4 demonstrated the effect of alkalosis treatment (reduces lactate responses) by sodium bicarbonate (NaHCO3) ingestion on exercise-induced hormonal response. The NaHCO3 treatment resulted in a greater pH (reduced lactate), and blunted GH response to 90 seconds of cycle ergometer sprinting, compared to the placebo treatment. Hence, an exercise regimen with greater metabolic stress should cause greater anabolic hormone and catecholamine responses to resistance exercise.
Getting Bigger and Stronger With Increased Metabolic Demand
Exercise with vascular occlusion markedly enhances metabolite accumulation within the muscles and concomitant GH secretion.2,3 Although it has not been established whether acute increases in GH lead to local skeletal muscle hypertrophy during prolonged strength training, it has been suggested that a transient increase of GH can produce an interaction with muscle cell receptors, aiding recovery and stimulation of hypertrophy.5
Another interesting fact is that there are many different peptides of the GH peptide, and responses should be taken into account because GH should not be regarded as a single hormone— but rather as a ‘family’ of related polypeptides that are all derived from one gene.6 This molecular heterogeneity may have physiological significance because the different peptides of GH have been shown to possess different biological activities and different effects on lipid, carbohydrate, and protein metabolism.6, 7, 8
In addition, it has been suggested that metabolic stress has a substantial role in stimulating muscular hypertrophy and strength gains. That’s right, not only can increasing metabolic demand cause increases in size— but also strength. For example, Schott et al.9 reported that an isometric training regimen resulted in a greater decrease in intramuscular pH (increased lactate production), and induced a greater muscle hypertrophy, compared to a regimen with only a small change in pH.
A previous research study revealed that improvement in strength following six weeks of dynamic resistance training was significantly greater in the regimen without rest, compared to a regimen with a 30-second rest period between each repetition— although the magnitude of muscular hypertrophy was not evaluated.10 The enhanced metabolic accumulation within muscles caused by vascular occlusion resulted in marked increases in muscular strength11 and muscle cross-sectional area12 following resistance training.
These findings suggest that exercise-induced metabolic changes may be associated with muscular adaptations to resistance training. Moreover, these effects might be induced, in part, by secretion of anabolic hormones, but no previous studies have been conducted on the influences of exercise-induced metabolic changes on acute hormonal responses and long-term adaptations of muscles.
Increasing Metabolic Demand with Eccentric Exercise
As mentioned previously, incorporating eccentric contractions is a great way to increase muscle mass because you can handle a heavier weight while lowering the weight as opposed to lifting the weight. The only problem with using eccentric exercise with maximum weights is that it only produces small increases in metabolic demand.
For example, studies using ‘eccentric only’ exercise produce very small increases in lactate responses. Researchers from Finland decided to investigate which eccentric load induced the greatest metabolic effect. As discussed earlier, increasing the metabolic demand can increase muscle hypertrophy and strength— so incorporating eccentric exercise with increased training load (weight) and increasing metabolic demand (increased lactate) can produce a dual hypertrophy response.
Researchers had subjects first perform the maximum strength measurements consisting of four conditions with different eccentric (ECC) loads. The four different load levels used for the ECC phase were 60, 70, 80, and 90 percent of concentric 1 RM, whereas the concentric (CON) resistance was sustained at 70 percent of concentric 1 RM. The researchers used a device that allows a person to overload the eccentric portion, while a spring-loaded device unhoists the weight so you can use a lighter concentric weight.
The weight releasers have the potential to maximize the resistance in the ECC phase and to reduce it during the CON phase of the movement. The weight releaser is detached from the strength-training bar at the end of the ECC phase of the movement, whereas the CON phase can be performed with a lower resistance.
The weight releasers detach from the bar and remain at the floor after the exercise is performed. Therefore, an assistant returns the weight releasers on the bar after each repetition, for consecutive repetitions. A hook is placed on the end of the barbell and then you lower a heavier weight. When the bottom hits the ground, the hooks are released and a lighter concentric weight can be lifted.
The study showed that the largest increase was observed in blood lactic acid concentrations from pre- to post-loading during 90 percent eccentric loading/70 percent concentric loading.13 The loading-induced increase in GH concentrations during the 90/70 percent loading tended be larger, compared to the other conditions. The study suggests that 90 percent eccentric loading/70 percent concentric loading leads to the greatest metabolic response, because the increase in blood lactate in the 90/70 percent condition was higher than the 70/70 percent condition. When the loads are expressed differently, the optimal ECC load in the study was 1.2 times the concentric resistance.
Thus, tension overload combined with enhanced metabolic stress may enhance muscle growth compared to performing eccentric exercise alone or ‘pure negatives.’ The combination of enhanced metabolic stress (i.e., enhanced lactate) and tension overload can enhance the muscle hypertrophy response.
If you are going to try this type of workout to enhance muscle mass, you are going to need spotters to help assist with unloading the weight. Another alternative is to use machines. For example, let’s say your maximum bench press is 200 pounds. You would load the machine with 170 and lift the weight, and then have your workout partner push against the bar.
Article source: muscular development