SEMI-TETHERED LOAD-VELOCITY PROFILES – CORRELATIONS WITH METABOLIC AND DRYLAND STRENGTH PARAMETERS IN MALE AND FEMALE SQUAD SWIMMERS

INTRODUCTION: Semi-tethered load-velocity profiling is a reliable method to estimate swim-specific neuromuscular capacities, i.e., theoretical maximal load (L0), speed (v0), and slope of the regression line (Slv), and can therefore be used for individual athlete characterization and training derivations (Olstad et al., 2020). For example, higher L0 and v0 values were observed in male compared to female front crawl swimmers (Olstad et al., 2020), higher L0 and lower v0 values were found in butterfly swimmers compared to front crawl swimmers (Gonjo et al., 2020). Despite high correlations between load-velocity profiles and 50 m performance (Gonjo et al., 2020), it is still unclear which metabolic or mechanical properties are associated with different semi-tethered load-velocity profiles. Therefore, we correlated anthropometric, dryland strength, and metabolic parameters with L0, v0, and Slv to elucidate underlying mechanisms between different profiles separately by sex.
METHODS: 12 male and 9 female (inter-)national-level squad swimmers (FINA points: 729 ± 68) completed 4 separate testing sessions in a randomized order. Besides anthropometric (height, mass, and arm span) and dryland neuromuscular assessment (squat and bench press 1 repetition maximum [1RMSQ, 1RMBP]), metabolic parameters (energy cost of swimming and maximal lactate accumulation rate [ċLamax]) were determined in water using a 500 m submaximal and 20 s sprint test, respectively. In addition, semi-tethered load-velocity profiles were determined from five ~20-m front crawl sprints, with loads increasing from 1 kg by 2 kg for male and 1 kg for female athletes, and speed recorded at 333 Hz by a robotic resistance device. From the linear regression of load (x) and speed (y), L0 (x-intercept), v0 (y-intercept), and Slv (-v0/L0) were calculated. Associations between metabolic and mechanical parameters and L0, v0, and Slv were examined separately by sex using Pearson correlation r.
RESULTS: L0, v0, and Slv were 21.3 ± 4.8 and 16.5 ± 2.9 kg, 1.88 ± 0.06 and 1.66 ± 0.06 m∙s-1, and -0.09 ± 0.02 and -0.10 ± 0.02 -m∙s-1∙kg-1 in male and female swimmers, respectively. Regarding anthropometry, mass (75.9 ± 8.0 and 70.1 ± 8.2 kg) correlated moderately with L0 in male (r = .55, p = .06) and with Slv in male (r = .52, p = .08) and female (r = .51, p = .16) athletes. ċLamax (0.50 ± 0.12 mmol∙L-1∙s-1) was the only metabolic parameter highly related to v0 in male athletes (r = .68, p = .02). Regarding dryland strength, 1RMSQ (75.9 ± 8.0 and 70.1 ± 8.2 kg) was moderately (r ≥ .51, p ≤ .13) and 1RMBP (75.9 ± 8.0 and 70.1 ± 8.2 kg) highly correlated with both L0 and Slv (r ≥ .76, p ≤ .03) in male and female athletes, while 1RMSQ and 1RMBP were only moderately associated with v0 in female athletes (r ≥ .54, p ≤ .16).
DISCUSSION: While moderate to high correlations were observed between mechanical parameters (especially 1RMBP) and L0 as well as Slv in both sexes, v0 was only moderately correlated with dryland strength in female athletes and highly correlated with anaerobic power (ċLamax) in male athletes. Thus, female swimmers might benefit from dryland strength training to increase v0, whereas males might benefit from anaerobic swim training. In both sexes, L0 might be improved by dryland strength training, especially for the upper body.
REFERENCES:
Gonjo et al. (2020). Relationships between a Load-velocity Profile and Sprint Performance in Butterfly Swimming. Int J Sports Med, 41(7), 461–467.
Olstad et al. (2020). Reliability of Load-Velocity Profiling in Front Crawl Swimming. Front Physiol, 11, 574306.