Comparing high-intensity resistance training incorporating periodic eccentric-only exercise with blood flow restriction training in older men: physiological responses and exercise feasibility

AIM: This study aimed to compare the feasibility, strength adaptations, and physiological effects of high-intensity resistance training incorporating periodic eccentric-only exercise (HIRT) with blood-flow restriction training (BFRT) in older men. METHODS: This three-group randomized controlled trial included 63 older men assigned to lower limb HIRT, BFRT, or a non-exercising control group for 12 weeks. BFRT was at 40% one-repetition maximum (1RM) and HIRT altered between eccentric-only exercises at 120% 1RM and traditional resistance exercise at 80% 1RM in a 1:3 ratio. Outcome measures included ratings of perceived exertion (RPE), delayed onset muscle soreness (DOMS), lactate and creatine kinase (CK) levels, 1RM and adverse events. RESULTS: BFRT was associated with higher RPE and more frequent training till failure, as well as greater lactate responses. Eccentric sessions in HIRT resulted in higher DOMS and CK levels. Both interventions significantly improved 1RM compared to controls, with HIRT demonstrating greater strength gains in leg extension and leg press. Adverse events included elevated blood pressure (n=1) and headache (n=2) in BFRT, and knee pain (n=2) in HIRT. CONCLUSION: Both interventions were effective but imposed different physiological demands, with BFRT inducing greater metabolic and HIRT greater mechanical stress. HIRT led to slightly greater strength gains, while BFRT remains a viable alternative for those unable to perform high-load exercise. Incorporating eccentric exercise may further optimize adaptations and manage muscle damage.