Effect of Different Loads on Stroke and Coordination Parameters During Freestyle Semi-Tethered Swimming

Abstract

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.

Relationships between a Load-velocity Profile and Sprint Performance in Butterfly Swimming

“…1). The mean V adj during the three cycles was plotted as a function of the external load (kg), and a linear regression line was established individually based on the load-velocity plot [16]. The mean V adj was selected for the analysis because it has been reported that plotting the mean velocity produces more accurate load-velocity profiles than using the maximum velocity data on land exercises [11].…”

“…To predict the maximum velocity and load, it is important to minimise the number of trials to avoid fatigue. It has been reported that the load-velocity relationship is expressed as a linear line with the coefficient of determination (R 2 ) of 0.98 [16], which implies that a small number of trials might be sufficient and appropriate for performance prediction. Therefore, swimmers were instructed to perform semi-tethered swimming with three different loads (1, 5, and 9 kg) with their maximum effort.…”

“…This suggests that the random error relating to the linear regression should be small in all swimming strokes. However, it has been reported that the amount of external load affects the coordination of the upper limbs in the front crawl [16]. Furthermore, a shift in upper-limb coordination in backstroke swimming with a change in swimming velocity has also been observed [20].…”

“…A load-velocity relationship in swimming could potentially be observed from several maximum-effort swimming trials with different external loads (semi-tethered swimming). Theoretically, both maximum swimming velocity and load could then be estimated with the same principle as the strength exercise studies because the swimming velocity and external load also have a linear relationship (with R 2 = 0.98) [16]. Even though load and force are different concepts, the predicted maximum load should be strongly related to the propulsive forces because the backward force due to the external load should be equal to the forward force produced by the swimmer's motion when the forward velocity is zero.…”

“…There have been several studies that applied a semi-tethered swimming method to assess swimming power [7,8,[16][17][18][19]. However, semi-tethered swimming has not been adopted to estimate maximum swimming velocity and load in any studies.…”