Mechanical power output is a reliable predictor of swim speed in front crawl. However, a complete power curve (power vs. load) has not been described for swimming, and intra-cycle power has not been assessed. The purpose of this study was to examine intra-cycle power output at propulsive phases and to determine maximum swimming power, the corresponding load and swimming speed. 18 swimmers (age 22.10±4.31years, height 1.79±0.07 m, arm span 1.85±0.08 m and body mass 76.74±9.00 kg) performed a swim power test. It consisted of 12.5 m all-out swims with only the arms, with a load attached to the swimmer. A linear encoder and a load cell recorded intra-cycle speed and force in each trial. The test was recorded with 2 underwater cameras. Intra-cycle power was obtained for propulsive stroke phases (pull: 60.32±18.87 W; push: 71.21±21.06 W). Peak power was 114.37±33.16 W. Mean maximum swim power was 66.49 W (0.86 W/kg), which was reached at a swimming velocity of 0.75 m/s with a 47.07% of the individual maximal load. Significant positive correlation (r=0.76, p<0.01) between maximum swim power and maximum swim speed was observed. These results suggest that the proposed test may be a training tool that is relatively simple to implement and would provide swimmers and coaches with quick feedback.

The aim of this study was to analyse to what extent the use of different loads modifies freestyle stroke and coordination parameters during semi-tethered swimming, and to examine whether those changes are positive or negative to swimming performance. First, behaviour of swimming speed (v), stroke rate (SR) and stroke length (SL) with increasing loads was examined. Secondly, mean and peak speed of propulsive phases (propvmean and propvpeak) were analysed, as well as the relative difference between them (%v). Finally, index of coordination (IdC) was assessed. Eighteen male swimmers (22.10±4.31years, 1.79±0.07m, 76.74±9.00kg) performed 12.5m maximal sprints, pulling a different load each trial (0, 1.59, 2.21, 2.84, 3.46, 4.09, 4.71, 5.34, 5.96, 6.59, 7.21 and 7.84kg). Rest between repetitions was five minutes. Their feet were tied together, keeping a pull-buoy between legs and isolating the upper limb action. A speedometer was used to measure intra-cycle speed and the test was recorded by a frontal and a lateral underwater cameras. Variables v and SL decreased significantly when load increased, while SR remained constant (p<0.05). Propvmean and propvpeak decreased significantly with increasing loads (p<0.05). In contrast, %v grew when load rose (r = 0.922, p<0.01), being significantly different from free swimming above 4.71kg. For higher loads, swimmers did not manage to keep a constant velocity during a complete trial. IdC was found to increase with loads, significantly from 2.84kg (p<0.05). It was concluded that semi-tethered swimming is one training method useful to enhance swimmers’ performance, but load needs to be individually determined and carefully controlled.

This study aimed to determine which contractile properties measured by tensiomyography (TMG) could better differentiate athletes with high- and low-power values, as well as to analyse the relationship between contractile properties and power production capacity. The contractile properties of the vastus medialis (VM), rectus femoris (RF) and vastus lateralis (VL) of an Olympic women's Rugby Sevens team (n = 14) were analysed before a Wingate test in which their peak power output (PPO) was determined. Athletes were then divided into a high-power (HP) and a low-power (LP) group. HP presented an almost certainly higher PPO (9.8 ± 0.3 vs. 8.9 ± 0.4 W kg, ES = 3.00) than LP, as well as a very likely lower radial displacement (3.39 ± 1.16 vs. 5.65 ± 1.50 mm, ES = 1.68) and velocity of deformation (0.08 ± 0.02 vs. 0.13 ± 0.03 mm ms, ES = 1.87) of the VL. A likely lower time of delay was observed in HP for all analysed muscles (ES > 0.60). PPO was very largely related to the radial displacement (r = -0.75, 90% CI = -0.90 to -0.44) and velocity of deformation (r = -0.70, 90% CI = -0.87 to -0.34) of the VL. A large correlation was found between PPO and the time of delay of the VL (r = -0.61, 90% CI = -0.84 to -0.22). No correlations were found for the contractile properties of RF or VM. These results highlight the importance of VL contractile properties (but not so much those of RF and VM) for maximal power production and suggest TMG as a practical technique for its evaluation.

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