Evaluation of strength, skin temperature and muscle activation in traditional and eccentric training in Paralympic Powerlifting athletes

Abstract

Paralympic Powerlifting (PP) is a maximum strength modality, where male athletes demonstrated greater relative and absolute strength compared to conventional powerlifting. This study aimed to assess the acute effects of traditional training (TT) and eccentric training (ET) methods on Maximum Isometric Strength (MIF), Time to Maximum Isometric Force (Time), Muscle Activation (sEMG), and Skin Temperature (Thermo) in twelve male PP athletes (mean age 30.25 ± 8.13; body weight 72.36 ± 18.47). The training consisted of 5 sets of 5 repetitions (5 × 5), with 80% 1RM in the TT method and in the ET 80% was adopted in the concentric phase and 110% in the eccentric phase, adopting a minimum rest of 3 min between sets and the cadence used was approximately 2 s in the eccentric phase and 1 s in the concentric phase for the ET and 1 s in each phase for the TT. Athletes competing nationally and internationally underwent Thermo, Time, and MIF assessments during TT (80%-1RM for both concentric and eccentric phases) and ET (80%-1RM concentric and 110%-1RM eccentric) at pre-training, post-training, 24 h, and 48 h. sEMG was evaluated in the clavicular portion of the pectoralis major (PMCP), sternal portion of the pectoralis major (PMSP), anterior Deltoid (AD), and Triceps Brachii (BT) during the final series (5 sets of 5 repetitions) of a training session. Athletes exhibited thermal differences in the PMCP muscle at 24 h between TT and ET (p = 0.020); Also, after the first 24 h, the AD showed differences between ET and TT (p = 0.016) and BT demonstrated differences between ET and TT (p = 0.028). The sEMG showed no significant differences between TT and ET (p > 0.05). The MIF displayed differences after 48 h between TT and ET (p = 0.004). The time showed no significant difference between TT and ET (p > 0.05). In conclusion, muscles involved in the bench press exhibited a significant increase in skin temperature with the ET method compared to TT, suggesting greater muscular fatigue. Furthermore, a higher MIF production was observed after the application of the TT in relation to ET, 48 h after training. In the ET, a lower MIF was observed than in the TT, indicating greater fatigue in this type of training.

Keywords: Muscle strength; Paralympic Powerlifting; Strength training; Surface electromyography; Thermography.

Fig. 1

Illustration of thermal images at before, after, 24 h and 48 h in TT and ET, respectively.

Fig. 2

Illustration of the regions of interest (ROI) in the thermal images acquired.

Fig. 3

The muscle electrical activity through surface electromyography (sEMG) (A) Peak and (B) Average, of the different muscle groups. Legend: Pectoralis Major Sternal Portion (P. Sternal), Pectoralis Major Clavicular Portion (P. Clavicular), Anterior Deltoid (Deltoid), Triceps Brachii, Long Head (Triceps). Values represented by mean and standard deviation.

Fig. 4

Skin temperature in the muscles (A) pectoralis major sternal portion, (B) pectoralis major clavicular portion, (C) anterior deltoid, and (D) Brachii Triceps, in the moments before, after, 24 h, and 48 h. Values represented by mean and standard deviation.

Fig. 5

(A) Maximal isometric force (MIF) and (B) Time until maximum isometric force (Time), in the moments before, after, 24 h and 48 h later. Values represented by mean and standard deviation.