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Effect of Two Different Isokinetic Training Protocols on Functional Hamstrings-to-Quadriceps Ratios: 1693 Board #346 June 2, 9: 00 AM - 10: 30 AM.

Functional hamstrings-to-quadriceps (H:Q) strength ratio is frequently assessed by isokinetic dynamometry in order to calculate the relationship between knee flexors and knee extensors and therefore determine knee muscle balance. This ratio approximates functionality because it considers hamstrings eccentric (ECC) strength in the deceleration of anterior tibial shear or rotation induced by quadriceps concentric (CON) strength. However, little is known about the effect of different strength training protocols on functional H:Q ratios. PURPOSE:To compare 2 different training protocols on functional H:Q ratio. METHODS:Twelve untrained subjects (age 23.75 ± 2.56 yrs, mass 72.53 ± 10.74 kg, ht 174.78 ± 6.02 cm) performed 6 weeks of strength training of their dominant knee flexors and extensors on a Biodex isokinetic dynamometer. They were randomly assigned to 3 training groups; concentric quadriceps and eccentric hamstrings (CON/ECC), eccentric quadriceps and eccentric hamstrings (ECC/ECC), and no training (CNTRL). Training began with 1 set of 10 maximal repetitions at 210°/s concentrically and 60°/s eccentrically. Intensity of training was increased every week by decreasing the angular velocity for concentric and increasing it for eccentric in 30°/s increments. Volume of training was increased by adding 1 set each week. All training sessions were separated by at least 48 hours. Concentric quadriceps and eccentric hamstrings strength were tested 72h before and after training, and functional H:Q ratios were calculated. RESULTS:There were no significant differences between groups for functional H:Q ratios at pre test (ECC/ECC = 0.79 ± 0.04; CON/ECC = 0.84 ± 0.15; and CNTRL = 0.66 ± 0.15). However, ECC/ECC group had a greater functional H:Q ratio at post test (0.86 ± 0.05), compared to CON/ECC (0.65 ± 0.04) and CNTRL (0.70 ± 0.15). CONCLUSIONS:These findings suggest that ECC/ECC training is more effective at increasing the H:Q functional ratio. This may be due to exclusive eccentric hamstrings strength training with no quadriceps concentric strength training. Eccentric training increases eccentric strength, therefore increasing the functional H:Q ratio.