Bilateral Facilitation During The Squat Jump Is Not Affected By Training State In College-aged Women.

Abstract

Bilateral deficit in strength and power have been reported and several studies suggest that training state may impact the apparent deficit. PURPOSE: To investigate bilateral deficit during jumping in women. METHODS: Athlete (ATH, n=18) and non-athlete (C, n=5) women gave informed consent to participate in this university approved study. ATH included participants in intercollegiate sports (volleyball, soccer, and track and field) while C were physically active but not playing organized sports. Subjects completed repeat trials of a 2-leg (2L) and single-leg (1L; left and right leg) squat jump without coutermovement while hands remained on hips. Data were averaged across trials. Jumps were conducted on individual force plates for 2L or singularly for 1L. Jump height was calculated from flight time (HtFT) determined with an infrared optical timing system and from jump impulse from ground reaction force. RESULTS: Height (ATH: 178.2±4.9 cm; C: 163.3±4.4 cm) and body mass (ATH: 75.6±9.3 kg; C: 59.8±3.3 kg) were greater in ATH, but ATH were younger (ATH: 19.8±1.3 yrs; C: 23.0±1.2 yrs). 2L HtFT (ATH: 27.6±0.5 cm; C: 27.3±0.5 cm) and 1L HtFT (left & right: ATH: 12.9±0.3 & 12.8±0.3 cm; C: 12.0±0.4 & 12.7±0.4 cm, respectively) were not different between groups (p>0.05) with 2L being greater than either 1L jump (p=0.001). To accomplish the same 2L jump height both groups produced a greater jump impulse in one leg (ATH: 90.7±12.2 N; C: 81.1±15.2 N) vs the other leg (ATH: 73.7±13.9 N; C: 59.6±11.9 N; p=0.01). This greater leg jump impulse during 2L was similar to that observed in the same leg during 1L (ATH: 112.3±25.3 N, p=0.63; C: 84.8±18.1 N; p=0.81). In contrast, the jump impulse of the other leg during 2L was less than that observed in the same leg during 1L (ATH: 106.0±16.4 N; C: 116.0±33.1 N). 2L jump height calculated from jump impulse overestimated (ATH: 34.1±1.1 cm, C: 40.1±1.3 cm) and underestimated (ATH: 18.6±2.1; C: 20.1±2.8 cm) 2L HtFT. The asymmetry index (AI=L-R/L+R) for jump impulse during 2L was 10.4% in ATH and 15.7% in C. CONCLUSION: A bilateral facilitation rather than defecit was observed in ATH and C during 2L jump. Jump performance was facilitated during 2L jumps by producing an impulse equivalent to that of a 1L jump in one leg. Participation in intercollegiate sports does not appear to alter this jumping strategy in women.