Acute Physiological Effects of Drop Set on IGF and GH in the Quadriceps Femoris Among Males in Kakamega County, Kenya

Abstract

Background: Resistance training (RT) for muscle growth (hypertrophy training – HT) theoretically optimizes the mechanical tension placed on the working muscle, which may be key to activating hypertrophic mechanisms. After prolonged HT, specialized weightlifting techniques like drop set training (DS) – or lifting progressively reduced loads without recovery – may help overcome plateaus in strength and re-stimulate hypertrophy, but physiological evidence to potentially support this hypothesis or the efficacy of implementing an acute drop set protocol in comparison to maintaining a standard hypertrophy training program is lacking. Objective: This objective of this study was to assess the levels of plasma growth hormone, and IGF during drop set and concentric exercises. Methods: The study used a randomized controlled, counterbalanced, repeated measures design. A repeated measures design was used to minimize the inter-individual variability of the hypertrophic response to resistance training. Thirty young males participated in a randomized, counterbalanced, within-subjects design, a DS protocol (4 sets, 4 loads/set, 75-30% 1RM, minimal recovery between loads, 3-minute recovery intervals between sets) and, separated by at least 7 days, a HT protocol (4 sets, 75% 1RM, 3-minute recovery intervals between sets). Data was analyzed using a 2 (Training Type: DS, HT, levels of quadriceps muscle hypertrophy) ´ 2 (Time: pre-exercise, post-exercise) repeated measures ANOVA to test the differences in concentrations of IGF-1 and GH during DS and HT at the specified time points. Results: The study found that there was a significant difference in IGF 1 levels before and after the exercise for both groups (Drop set and concentric exercise), with a p-value of .007. The interaction effect between the within-subjects factor (IGF 1 pre and post) and group was also significant. The results showed that there was a significant difference in GH levels before and after the exercise for both groups (Drop set and concentric exercise), with a p-value of < .001. For the Drop set group, GH pre was also significantly lower than GH post. It can be concluded that both the drop set and concentric exercise techniques have an impact on the levels of IGF 1, and GH in the quadriceps femoris. The study recommends that physical trainers and fitness professionals should consider using the Drop set exercise technique in their training programs for clients who are looking to improve their performance.