Impact of a Strength Intervention Program on Change of Hamstrings: Quadriceps Ratio and on Change of 1 Repetition Maximum

The relationship between the muscular strength of hamstrings and quadriceps and their possible muscular imbalance is considered by many authors as one of the causes of knee joint injury. The aim of this work is to assess the exercise program including squat modifications both in terms of progression of lower limb strength and in terms of possible change of H: Q ratio. Subjects were divided into five groups (one control, four experimental). The experimental groups practiced the intervention program twice a week for eight weeks (EX1: Barbell squat, EX2: Barbell half squat, EX3: Barbell half squat with countermovement). In one training session participants repeated the exercise five times in six series. All experimental groups exhibited significant differences in mean values (p < 0.01), indicating the progression of lower limb strength measured by 1RM for barbell squat. The differences in the mean values of the H: Q ratio measured on an isokinetic dynamometer in the isokinetic test mode at angular velocities of 60 and 300 degrees per second did not show statistically significant differences (p = 0.99338). The established strength intervention program is suitable for the development of lower limb strength and does not show any changes in the H: Q ratio

Transfer of Muscle Strength Between Single-Joint and Multi-Joint Exercises for Lower Limbs

Most strength and conditioning coaches deal with the question of how to supplement specific exercises, or which non-specific exercises would be the most suitable for achieving a set purpose. This study aims to assess strength transfer with a focus on the lower limbs projected from a selected strength intervention program (the right leg exercises only single-joint exercises: leg extension on machine and leg curl; the left leg exercises only multi-joint exercises: deadlift and leg press) to the force of the knee joint flexors and extensors during eccentric and concentric contractions. In one training session, the participants repeated every exercise five times in four series. The load intensity was around 90% of 1RM and was increased by 5% after the first and the fifth week. The rest interval was always three minutes long. For the left lower limb, the highest transfer (0.20) was from the leg press to the knee joint extensor at the eccentric contraction and from the deadlift was the highest transfer (0.19) to the knee joint extensor at the eccentric contraction. For the right lower limb, the highest transfer (0.53) was from the leg extension on a machine to the knee joint flexor at the concentric contraction and from the lying leg curl was the highest transfer (0.47) to the knee joint flexor at the concentric contraction