Int J Sports Physiol Perform. 2019 Jul 1;14(7):966-971. doi: 10.1123/ijspp.2018-0745.
Critical speed (CS) and supra-CS distance capacity (D') are useful metrics for monitoring changes in swimmers' physiological and performance capacities. However, the utility of these metrics across a season has not been systematically evaluated in high level swimmers.
Twenty-seven swimmers (18 female; age 19.1 ± 2.9 y, 9 male; 19.5 ± 1.9 y, mean ± SD) completed the 12x25m swimming test multiple times (4 ± 3 tests/swimmer) across a two-year period. Season-best times in all distances for the test stroke were sourced from publicly available databases. Swimmers' distance speciality was determined as the event with the time closest to world record. Four metrics were calculated from the 12x25m test: CS, D', peak speed and drop off %.
Guyatt's Responsiveness Index values were calculated to ascertain the practically relevant sensitivity of each 12x25m metric: CS = 1.5, peak speed = 2.3, D' = 2.1 and drop off % = 2.6. These values are modified effect sizes (ES); all are large effects. Bayesian mixed-modelling showed substantial between-subject differences between genders and strokes for each variable, but minimal within-subject changes across the season. Drop off % was lower in 200 m swimmers (14.0 ± 3.3%) compared to 100 m swimmers (18.1 ± 4.1%, p = 0.003, ES = 1.10).
The 12x25m test is best suited to differentiating between swimmers of different strokes and events. Further development is needed to improve its utility in quantifying meaningful changes over a season for individual swimmers.
临界速度（CS）和超 CS 距离能力（D'）是监测游泳运动员生理和表现能力变化的有用指标。然而，这些指标在高水平游泳运动员中的季节变化的应用尚未得到系统评估。
27 名游泳运动员（18 名女性；年龄 19.1 ± 2.9 岁，9 名男性；19.5 ± 1.9 岁，平均值 ± SD）在两年内多次完成 12x25m 游泳测试（每个游泳运动员 4 ± 3 次测试）。从公开数据库中获取了所有距离测试泳姿的最佳成绩。游泳运动员的距离特长根据最接近世界纪录的项目确定。从 12x25m 测试中计算出了四个指标：CS、D'、峰值速度和下降百分比。
计算了盖亚特反应性指数值，以确定每个 12x25m 指标的实际相关灵敏度：CS = 1.5，峰值速度 = 2.3，D'= 2.1，下降百分比 = 2.6。这些值是修正后的效应量（ES）；均为大效应。贝叶斯混合模型显示，每个变量的性别和泳姿之间存在很大的个体差异，但在整个赛季内个体差异很小。200 米游泳运动员的下降百分比（14.0 ± 3.3%）低于 100 米游泳运动员（18.1 ± 4.1%，p = 0.003，ES = 1.10）。
12x25m 测试最适合区分不同泳姿和项目的游泳运动员。需要进一步开发，以提高其在量化个体游泳运动员整个赛季内有意义变化方面的应用。
