Body Responses to Three Different Resistance Training Intensities

Take Home Points

Exercise intensity during the resistance exercise is important for the enhancement of lactate responses, but the slow resistance exercise method could induce acute neuromuscular response as much as high intensity methods.

Resistance training is known to be beneficial for health and performance, the most beneficial method is still not known. Resistance training programs are specific to training goals of individuals and their daily physical demands. A resistance training program can be described with many acute training variables such as training intensity, volume, repetition numbers, rest intervals, contraction speed and other variables (Arazi 2014).

To achieve optimal muscle hypertrophy and strength, exercise intensity should be middle to high (≥65% of 1 RM). Authors suggest that mechanical stimuli are essential and represent the major determinant of resistance training adaptation (Arazi 2014). Some researchers have suggested that metabolic and hormonal changes are important for hypertrophy and strength gain as well. For this claim, several resistance training methods have been developed like slow, super slow and modified vascular occlusion to compare metabolic and hormonal changes (Arazi 2014). The similarity between these methods is the training intensity being low to middle (20-50% of 1 RM).

Arazi (2014) compared the effects of resistance exercise with three different methods on integrated electromyography (IEMG) and metabolic responses in recreational athletes. Twenty four males (23 years old) were randomly assigned to three experimental groups. Participants performed knee extension exercises: Slow (SL: 3-3, 3s for each concentric and eccentric action with 50% of 1 RM), Normal (NH: 1-1, 1 s for each concentric and eccentric action 80% of 1 RM) and Traditional (TH: 2-4, 2s for concentric and 4s for eccentric action with 80% of 1 RM). Plasma lactate, glucose and triglyceride concentration and IEMG was measured before and immediately after performing four sets of resistance exercise. Each method significantly decreased IEMG, but there was no significant difference between groups. Lactate was increased following TH and NH more than SL method. Each method significantly increased plasma glucose. Work considering time under tension was higher during TH method than the other methods and during SL it was higher than NH method. Volume load was higher during NH than the other two methods and during TH it was higher than SL method. These results indicate that exercise intensity during the resistance exercise is important for the enhancement of lactate responses, but the slow resistance exercise method could induce acute neuromuscular response as much as high intensity methods. It seems that this method will be advantageous for those who want to increase acute neuromuscular changes with low exercise intensity and volume.

According to the stimulus-tension theory, the intensity and duration of the muscular tension are responsible for neural and morphological adaptations (Arazi 2014). The interesting result of this study is that SL method could stimulate IEMG as much as NH and TH methods. Even though training intensity, volume and pressure on joints was lower. The other interesting finding of this research is that SL method could decrease total number of repetition as much as NH and TH methods, even though exercise intensity was lower in SL (Arazi 2014). This is maybe because of more fatigue caused by SL than high speed methods. These results indicate that high intensity resistance exercise causes higher lactate response, but slow resistance exercise method could induce acute neuromuscular response as much as high intensity methods (Arazi 2014). This method seems to be advantageous for those who want to increase acute neuromuscular changes with low exercise intensity and volume.

Reference:

1. Arazi H, Mirzaei B, Heidari N. Neuromuscular and metabolic responses to three different resistance exercise methods. Asian J Sports Med. 2014 Mar;5(1):30-8. Epub 2013 Oct 29.

Written by Chris Barber, CPT