| Summary: | M. Comm. === One function of skeletal muscle is to serve as the body's shock absorbers and thus dampen rates of loading (ROL) around joints during activities. However, it is not clear whether individuals with strong leg muscles actually demonstrate different ROL during gait than weaker individuals. The aim of this cross-sectional study was to determine the significance of muscle strength on ROL during gait. Females (ages 18 to 50) were solicited via advertisement and screened via phone interviews. Subjects (n=56) were chosen and placed into one of three groups based on training history: Strength Trained (ST), Aerobically Trained (AT), and Sedentary (S). Subjects walked barefoot (10 trials) over an 8 m walkway while ROL was sampled using a 1000 Hz force platform (AMTI OR6-6). Gait speed was controlled between 2.22 - 2.45 m.s -1 using telemetric photocells placed three meters apart. Maximum concentric and eccentric quadriceps and hamstring strength were measured at 90 degrees•s -1 using an isokinetic dynamometer (KINCOM 500H). Peak torque was divided by body weight to determine relative strength (Nrn-kg -1 ). Statistical analyses (p<0.05) included ANOVA and the Bonferroni/Dunn post-hoc test. There were no significant differences in age, height or walking speed across groups. The S group (78.3 ± 15.6 kg, n=18) weighed significantly more than the AT (60.5 ± 8.0 kg, n=19) and ST (63.1 ± 10.7 kg, n=19) groups. Body composition analyses showed that the mean body fat percentage of the S group (34.8 ± 7.3 %, n=18) was significantly higher than both AT (22.3 ± 5.7 %, n=19) and ST (23.2 ± 6.9 %, n=19) groups. Relative concentric and eccentric strength of the quadriceps of the AT (2.02 ± 0.07, n=19; 3.49 ± 0.18, n=19 respectively) and ST (2.1 ± 0.08, n=19; 3.50 ± 0.14, n=19 respectively) groups were significantly greater than the S (1.68 ± 0.07, n=18; 2.63 ± 0.10, n=18 respectively) group. Relative concentric hamstrings strength of both the AT (1.07 ± 0.05, n=19) and ST (1.08 ± 0.04, n=19) groups were significantly greater than the S (0.91 ± 0.04, n=18) group. Relative eccentric hamstring strength of only the ST (1.60 ± 0.07, n=19) group was significantly greater than the (1.34 ± 0.08, n=18) group. There were no significant differences in ROL between the S (2.21 ± 0.15 %Wt.ms -1 , n=18) and AT groups (2.14 ± 0.15 %Wt-ms 1 , n=19) (p=0.70), and the AT (2.14 ± 0.15 %Wt.ms-1 , n=19) and ST (1.82 ± 0.10 %Wt.ms -1 , n=19) (p=0.10) groups. However, the females in the ST (1.82 ± 0.10 %Wt•ms -1 , n=19) group had significantly lower ROL than the females in the S group. In addition, females in the ST group demonstrated a lower frequency of heelstrike transient (HST) occurrence. Seven of the S (n=18) females demonstrated HST while only four of the ST (n=19) females did. In conclusion, strength trained females demonstrated significantly lower rates of loading during gait than those in the sedentary group. High ROL have been associated with knee pain and osteoarthritis. These findings suggest that strength training may decrease the risk for these maladies.
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