Selected immunoendocrine and performance adaptations to upper-body plyometric training and β-alanine supplementation in male swimmers.

2026-05-31
Journal of the International Society of Sports Nutrition 23(1)
- Hui Gao
- Xuemei Yu
- Zhiyong Guo

PubMed: 42218755
DOI: 10.1080/15502783.2026.2679050

Study Design

Type: Randomized Controlled Trial (RCT)
Population: thirty trained male swimmers (age: 25.7 ± 2.6 years; height: 1.83 ± 0.07 m; body mass: 81.6 ± 3.2 kg)
Methods: randomly assigned to one of three groups: PT + BA, PT + placebo (PL), or control (CON). Participants in the PT groups completed an 8-week upper-body PT program (2 sessions·week⁻¹). Participants in the supplementation groups ingested β-alanine (4.8 g·day⁻¹ divided into six 0.8 g doses) or a matched placebo daily throughout the intervention.
Blinding: Double-blind
Duration: 8 weeks

Background

Upper-body plyometric training (PT) enhances neuromuscular performance and power production. However, its application in swimming and its potential interaction with β-alanine (BA) supplementation remain largely unexplored. Therefore, this study investigated the combined effects of upper-body PT and BA supplementation on performance and immunoendocrine adaptations in trained male swimmers.

Methods

Thirty trained male swimmers (age: 25.7 ± 2.6 years; height: 1.83 ± 0.07 m; body mass: 81.6 ± 3.2 kg) were randomly assigned to one of three groups: PT + BA, PT + placebo (PL), or control (CON). Participants in the PT groups completed an 8-week upper-body PT program (2 sessions·week⁻¹). Each session consisted of upper-body plyometric exercises performed for 3-4 sets of 12-16 repetitions with 120 s rest between sets. Participants in the supplementation groups ingested β-alanine (4.8 g·day⁻¹ divided into six 0.8 g doses) or a matched placebo daily throughout the intervention. Assessments conducted before and after the intervention included medicine ball throw (MBT), push-up endurance, one-repetition maximum (1RM) bench press, swim ergometer peak and mean power output (PPO and MPO), and 50-, 100-, and 200-m freestyle performance. Blood samples were also collected pre- and post-intervention to determine testosterone, cortisol, and immunoglobulin A (IgA) concentrations.

Results

Both PT groups showed significant improvements in all performance outcomes compared with baseline (all p < 0.05), with effect sizes ranging from small to moderate. Post hoc analyses revealed a significant group × time interaction for MBT (p = 0.045), push-up endurance (p = 0.041), PPO (p = 0.026), and MPO (p = 0.033), indicating greater improvements in the PT + BA group than in the PT + PL group. In addition, following the training intervention, the PT + BA group showed significant changes in testosterone (p = 0.011), cortisol (p = 0.028), and IgA (p = 0.042) concentrations compared with the PT + PL group.

Conclusions

Eight weeks of upper-body PT significantly enhanced upper-body power, anaerobic capacity, and swimming performance in trained male swimmers. BA supplementation further amplified these training-induced adaptations and promoted a more favorable immunoendocrine adaptation profile. These findings suggest that combining upper-body PT with β-alanine supplementation may provide synergistic benefits for performance development and physiological recovery in competitive swimmers.

Research Insights

Beta-Alanine→Increased Mean Power Output
Post hoc analyses revealed a significant group × time interaction for ... MPO (p = 0.033), indicating greater improvements in the PT + BA group than in the PT + PL group.
Effect
Beneficial
Effect size
Small
Dose
4.8 g·day⁻¹ divided into six 0.8 g doses
Beta-Alanine→Increased Medicine Ball Throw Distance
Post hoc analyses revealed a significant group × time interaction for MBT (p = 0.045), ... indicating greater improvements in the PT + BA group than in the PT + PL group.
Effect
Beneficial
Effect size
Small
Dose
4.8 g·day⁻¹ divided into six 0.8 g doses
Beta-Alanine→Increased Peak Power Output
Post hoc analyses revealed a significant group × time interaction for ... PPO (p = 0.026), indicating greater improvements in the PT + BA group than in the PT + PL group.
Effect
Beneficial
Effect size
Small
Dose
4.8 g·day⁻¹ divided into six 0.8 g doses
Beta-Alanine→Increased Push-up Endurance
Post hoc analyses revealed a significant group × time interaction for ... push-up endurance (p = 0.041), indicating greater improvements in the PT + BA group than in the PT + PL group.
Effect
Beneficial
Effect size
Small
Dose
4.8 g·day⁻¹ divided into six 0.8 g doses
Beta-Alanine→Increased Serum Immunoglobulin A (IgA) Levels
the PT + BA group showed significant changes in ... IgA (p = 0.042) ... compared with the PT + PL group.
Effect
Beneficial
Effect size
Small
Dose
4.8 g·day⁻¹ divided into six 0.8 g doses
Beta-Alanine→Increased Testosterone Level
the PT + BA group showed significant changes in testosterone (p = 0.011) ... compared with the PT + PL group.
Effect
Beneficial
Effect size
Small
Dose
4.8 g·day⁻¹ divided into six 0.8 g doses
Beta-Alanine→Reduced Cortisol Levels
the PT + BA group showed significant changes in ... cortisol (p = 0.028) ... compared with the PT + PL group.
Effect
Beneficial
Effect size
Small
Dose
4.8 g·day⁻¹ divided into six 0.8 g doses