Front- or rear-weighted track start or grab start: which is the best for female swimmers?

The aim of this study was to compare three competitive swimming starts (grab, rear-weighted track, and front-weighted track). The starts were compared in terms of time and instantaneous horizontal velocity, both at take-off from the block and at 5 m from the wall. Twenty US college female swimmers performed three trials of each of the three randomly ordered starts. Swimmers left the block significantly sooner using the front-weighted track start (0.80 s) than the other two starts (both 0.87 s; P < 0.001). In the rear-weighted track start, however, the athletes left the blocks with significantly higher horizontal velocity than in the grab or front-weighted track start (3.99 vs. 3.87 and 3.90 m/s, respectively; each P < 0.001). By 5 m, the front-weighted track start maintained its time advantage over the grab start (2.19 vs. 2.24s; P = 0.008) but not the rear-weighted track start (2.19 vs. 2.21 s; P = 0.336). However, the rear-weighted track start had a significant advantage over the front-weighted track start in terms of instantaneous horizontal velocity at 5 m (2.25 vs. 2.18 m/s; P = 0.009). Therefore, the rear-weighted track start had a better combination of time and velocity than the front-weighted track start. There was also a trend for the rear-weighted track start to have higher velocity at 5 m than the grab start, although this did not reach statistical significance (2.25 vs. 2.20 m/s; P = 0.042). Overall, these results favour the rear-weighted track start for female swimmers even though most of the athletes had little or no prior experience with it. Additional research is needed to determine whether males would respond similarly to females in these three different swimming starts.

Manipulative treatment of carpal tunnel syndrome: biomechanical and osteopathic intervention to increase the length of the transverse carpal ligament: part 2. Effect of sex differences and manipulative "priming".

As a theoretical basis for treatment of carpal tunnel syndrome (CTS) and expanding upon part 1 of this study, the authors investigated the effects of static loading (weights) and dynamic loading (osteopathic manipulation [OM]) on 20 cadaver limbs (10 male, 10 female). This larger study group allowed for comparative analysis of results by sex and reversal of sequencing for testing protocols. In static loading, 10-newton loads were applied to metal pins inserted into carpal bones. In dynamic loading, the OM maneuvers used were those currently used in clinical settings to treat patients with CTS. Transverse carpal ligament (TCL) response was observed by measuring changes in the width of the transverse carpal arch (TCA) with three-dimensional video analysis and precision calipers. Results demonstrated maximal TCL elongation of 13% (3.7 mm) with a residual elongation after recovery of 9% (2.6 mm) from weight loads in the female cadaver limbs, compared to less than 1 mm as noted in part 1, which used lower weight loads and combined results from both sexes. Favorable responses to all interventions were more significant among female cadaver limbs. Higher weight loads also caused more linear translatory motion through the metal pins, resulting in TCA widening equal to 63% of the increases occurring at skin level, compared to only 38% with lower loads. When OM was performed first, it led to greater widening of the TCA and lengthening of the TCL during the weight loading that followed. Both methods hold promise to favorably impact the course of management of CTS, particularly in women.