Inspiratory muscles pre-activation in young swimmers submitted to a tethered swimming test: effects on mechanical, physiological, and skin temperature parameters

Abstract

Inspiratory muscles pre-activation (IM_PA) has been studied to improve subsequent performance in swimming. However, the effects of IM_PA on various parameters in swimmers are still unknown. Therefore, this study aimed to investigate the effects of IM_PA on the mechanical parameters, physiological responses, and their possible correlations with swimming performance. A total of 14 young swimmers (aged 16 ± 0 years) underwent a 30-s all-out tethered swimming test, preceded or not by IM_PA, a load of 40% of the maximal inspiratory pressure (MIP), and with a volume of 2 sets of 15 repetitions. The mechanical (strength, impulse, and fatigue index) and physiological parameters (skin temperature and lactatemia) and the assessment of perceived exertion and dyspnea were monitored in both protocols. The IM_PA used did not increase the swimming force, and skin temperature, decrease blood lactate concentration, or subjective perception of exertion and dyspnea after the high-intensity tethered swimming exercises. Positive correlations were found between mean force and blood lactate (without IM_PA: r = 0.62, P = 0.02; with IM_PA: r = 0.65, P = 0.01). The impulse was positively correlated with blood lactate (without IM_PA: r = 0.71, P < 0.01; with IM_PA: r = 0.56, P = 0.03). Our results suggest that new IM_PA protocols, possibly with increased volume, should be developed in order to improve the performance of young swimmers.

Figure 1

Experimental design used in the study (timeline configuration for the exercise and inspiratory muscle pre-activation (IM_PA) session). Randomly, each subject underwent two experimental sessions, one in the control condition and the other with IM_PA. Temporal representation of the interventions performed before, during and after the tethered swimming exercise during which the force recordings occurred. Thermographic records (skin temperature - ST), blood lactate samples and rating of perceived exertion (RPE) and dyspnea (RPD) were obtained during all the assessment sessions in the time windows shown.

Figure 2

(A) Force relativized to body mass (N kg⁻¹) during the tethered swimming trials (all-out) with and without IM_PA. The impulse (N s) is represented in grey by the area over the curve of the trapezoidal method. (B) Table of the mechanical parameters with and without IM_PA. Values taken as mean and statistical difference in interaction with P < 0.05 (n = 14).

Figure 3

Lower limb skin temperature (mean ± standard error of the mean) at four collected time points (at rest, after warm-up, before IM_PA and after the all-out swimming test) in different conditions (with and without IM_PA). A, D = significant difference compared to rest; b, e = significant difference compared to the time after WU; and C, F = significant difference compared to the time before IM_PA application; (G) anterior and posterior views of the lower limb skin temperature in the anatomical position; P < 0.05.

Figure 4

Upper limb skin temperature expressed as mean ± standard error of the mean at four collected times (at rest, after warm-up, before IM_PA and after the all-out swimming test in different conditions (with and without IM_PA). A, D = significant difference compared to rest; b, e = significant difference compared to the moment after WU; and C, F = significant difference compared to the moment before IM_PA application; (I) anterior and posterior views of the upper limb skin temperature in the anatomical position; P < 0.05.

Figure 5

Physiological and psychophysiological parameters before and after the all-out tethered swimming test. (A) Rating of perceived exertion and (B) rating perceived dyspnea without and with IM_PA: a, e = significant difference in relation to rest; b, f = significant difference in relation to the moment after WU; c, g = significant difference in relation to the moment after the all-out swimming test; and d, h = significant difference in relation to minute 5. (C) Blood lactate (mM) without and with IM_PA: a, f = significant difference with respect to rest; b, g = significant difference with respect to minute 1; c = significant difference with respect to minute 3; d = significant difference with respect to minute 5; and e = significant difference with respect to minute 7. Results expressed as mean and standard error of the mean; P < 0.05.