An assessment of isometric muscle strength and the hamstring: Quadriceps ratio among males trained with free weights vs. machines

Introduction. The purpose of this study was to assess the isometric muscle strength (IMS) of the knee extensors and flexors, bilateral asymmetry (BA) and the hamstring: quadriceps ratio (H:Q ratio) between the dominant leg (DL) vs. the non-dominant leg (NDL) of males trained with free-weights vs. machines. Material and Methods: Thirty males were recruited and separated into two groups: Free-weights (n = 15) and Machines (n = 15) groups. All study participants performed the IMS testing for knee extensors and flexors in the DL and NDL using a commercially available load cell. The highest value obtained from the three trials was used for statistical analysis. Results: The IMS of the quadriceps and hamstring muscles for DL and NDL showed a significant increase in the Free-weight group when compared to the Machine group. In addition, a significant difference (p <.03) in the IMS of hamstring muscles between DL vs. NDL was observed in the Machine group. The H:Q ratio on DL (p < .002) and NDL (p < .01) was significantly higher in the Free-weight group. Conclusion: This study showed better isometric muscle strength of the thigh (hamstring and quadriceps) and the H:Q ratio in males trained with free weights. In addition, males trained with machines showed a bilateral asymmetry of the hamstring muscles and a lower H:Q ratio – consequently, a higher risk of knee injuries.