Reliability of active drag assessment using an isotonic sprint protocol with resistance in human swimming
The descriptive statistics and the results of the reliability analyzes are presented in Tables 1 and 2, respectively. In both sexes, trials with an external load less than 3 kg showed Da result was observed (p Da measured with an external load of 7 and 9 kg were less than Da obtained from tests of 1, 3 and 5 kg. In females, all Da the values differed from those obtained in other trials, except for the comparison between 3 and 4 kg (p = 0.07).
A non-significant day effect for both genders showed that there was no systematic bias in assessing day-to-day reliability. The low ICC observed in 1 kg (males and females) and 2 kg (females), corresponding to Fto add from 16 to 27 N (Table 1), suggests that low resistance should not be used to assess Da with VPM and confirms the initial hypothesis. Nevertheless, the use of too high a resistance is also not recommended, as male swimmers have shown lower reliability when swimming. Da was assessed with 7 and 9 kg (Fto add= 80–102 N) compared to 3 and 5 kg load tests (Fto add= 37–60N). From a reliability perspective, researchers and practitioners should assess Da with Fto add from 37 to 60 N in male and female swimmers.
The inter-participant mean of Da ranged from 46 to 84 N in males and from 39 to 60 N in females (at the speed of approximately 1.82 m/s and 1.56 m/s, respectively), depending on the external load assigned to the swimmer. Also, the greater the external load used in VPM, the greater the Daas shown in Fig. 1. Although it is not possible to discuss the accuracy of the method as there is currently no method that directly measures Dacomparison of the results of the current study with the literature is useful to examine whether the results obtained Da in the present study is reasonably aligned with previous studies. Kolmogorov and Duplichcheva9 to analyse Da for the full-body crawl in males and females and reported that on average, males presented about 83 N at 1.78 m/s and females about 53 N at 1.60 m/s. These values were similar to the results of the present study (with an external load of 1 kg). Another study22 investigation Da in freestyle with the arms only using the MAD system and workbench Da equation for men (Da= 28.9v2.12) and females (Da= 20.4v2.28). These equations, in combination with the mean vmaximum in the present study, generate Da= 100.5 N for males and Da= 56.2 N for women. This Da for women is comparable to the result of the present study (when the resisted load was 1 kg). However, the Da the calculation for males produced a slightly higher value than the present study, which may be due to the fact that the previous study included water polo players in their samples22. However, a recent study23 assessed Da for both men and women using the assisted towing method and reported Da than other studies, including the present one (average Da= 89.0 N for females at v= 1.60 m/s, and mean Da= 140.5 N for males at v= 1.87 m/s).
Comparisons between previous studies and the present study showed that the results of the present study were closest to the literature when the external load for the VPM was 1 kg. Otherwise, Da calculated under heavy load conditions (such as 5–9 kg loads for males and 3–5 kg loads for females) were close to, or even lower than, the passive drag results reported in the literature. For example, Zamparo et al.24 showed passive drag of 70 N at 1.80 m/s and 47–60 N at 1.42–1.62 m/s for male and female competitive swimmers, respectively. These passive drag values are greater than Da found in the present study with loads of 5-9 kg (males) and 3-5 kg (females), indirectly suggesting that the Da obtained under high load conditions were probably underestimated.
These examples imply that there is probably a trade-off between accuracy and reliability of VPM, i.e. the lighter the external load, the more accurate but less reliable the load. Da results. As stated in the introduction, VPM is very sensitive to violation of its assumption that swimmer power output is equal between without and with external force/load conditions.ten. Since measuring power output during swimming is currently a very difficult task, it is unknown to what extent external force/load affects the power output of swimmers. However, assuming that the power output is more similar when the two conditions (with and without external resistance) are closer, it is reasonable to consider that the power output in a half-tethered condition is closer to free-swimming when assigning a smaller force. /load.
It is therefore necessary to choose the external load which makes it possible to obtain reliable results while avoiding assigning a heavy load to the swimmer. For male swimmers, since the 3 kg and 5 kg trials showed high reliability and there were no statistical differences in Da between these tests, Da evaluation with Fto add 37 to 60 N may also be recommended. In women, of the three trials that showed high reliability (3–4–5 kg), a 5 kg load produced a significantly lower load Da than 3 kg and 4 kg trials, which means that the underestimation of Da was probably more severe in the 5 kg trial than in the other two trials. Therefore, even if the evaluation Da with Fto add of 37 to 60 N could produce reliable results, limiting Fto add at 37–47 N might be preferable to minimize the underestimation of Da for females.
In conclusion, VPM can produce reliable results when assigning swimmers with a load of 3-5 kg (37-60 N Fto add) for male and female competitive swimmers, and awarding Fto add higher than the suggested range for swimmers may result in poor measurement reliability. The calculation Da results with this range of Fto add are probably underestimated. Nevertheless, due to its high reliability, VPM with Fto add from 37 to 60 N can be used to assess differences in Da between groups or to assess long-term change Da, as long as the same parameter is used. However, it is advisable to limit Fto add to 37–47 N for females due to underestimation of Da be more severe when assigning a larger Fto addas 60 N. The present study focused only on swimmers of post-pubertal age, but VPM has also often been used to assess Da among young swimmers16. Therefore, the reliability of this method for age group swimmers should be further investigated.