Purpose. Hamstring strain injuries (HSIs) are highly prevalent in sports. While the Nordic Hamstring Exercise (NHE) is used for prevention, and the Askling L-Protocol is employed for rehabilitation, their evidence has been examined in isolation. Methods. This systematic review evaluates and contrasts these protocols to clarify their distinct roles. Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines (PROSPERO: CRD420251128030), a systematic search of four databases identified randomised controlled trials (RCT) and quasi-experimental studies (2010–2025) in athletic populations. The risk of bias was assessed using Cochrane Risk-of-Bias 2 (RoB 2) tool and the Risk of Bias in Non-Randomised Studies of Interventions (ROBINS-I) tools, and results were narratively synthesised. Results. Twenty-five studies involving 2,613 athletes were included. For reports, a large cluster-RCT reported a substantial reduction in acute HSI incidence following an NHE programme [adjusted risk ratio (RR) = 0.293, 95% confidence interval (CI) 0.150–0.572], and a 10-week NHE trial reported a large gain in peak eccentric hamstring strength (ECC-PHS +62.3 N; p = 0.006; Cohen’s d = 0.92). For rehabilitation, two Askling trials reported shorter mean return-to-sport time with the L-Protocol than with conventional programmes (mean differences 23 and 37 days; p < 0.001 in both trials; 95% CIs not reported). Conclusions. Evidence from the included trials suggests that the NHE-based programmes can support prevention strategies, with several studies reporting improvements in eccentric strength and muscle architecture, and that the Askling L-Protocol is supported primarily by rehabilitation trials reporting shorter return-to-sport times. Overall, these findings indicate that the two protocols may serve different clinical purposes and should be selected according to the athlete’s stage on the injury continuum.
Prevention and rehabilitation of hamstring injuries through the Nordic and Askling protocols: a systematic review
LUCA POLI
;FRANCESCO FISCHETTI;STEFANIA CATALDI;GIANPIERO GRECO
2026-01-01
Abstract
Purpose. Hamstring strain injuries (HSIs) are highly prevalent in sports. While the Nordic Hamstring Exercise (NHE) is used for prevention, and the Askling L-Protocol is employed for rehabilitation, their evidence has been examined in isolation. Methods. This systematic review evaluates and contrasts these protocols to clarify their distinct roles. Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines (PROSPERO: CRD420251128030), a systematic search of four databases identified randomised controlled trials (RCT) and quasi-experimental studies (2010–2025) in athletic populations. The risk of bias was assessed using Cochrane Risk-of-Bias 2 (RoB 2) tool and the Risk of Bias in Non-Randomised Studies of Interventions (ROBINS-I) tools, and results were narratively synthesised. Results. Twenty-five studies involving 2,613 athletes were included. For reports, a large cluster-RCT reported a substantial reduction in acute HSI incidence following an NHE programme [adjusted risk ratio (RR) = 0.293, 95% confidence interval (CI) 0.150–0.572], and a 10-week NHE trial reported a large gain in peak eccentric hamstring strength (ECC-PHS +62.3 N; p = 0.006; Cohen’s d = 0.92). For rehabilitation, two Askling trials reported shorter mean return-to-sport time with the L-Protocol than with conventional programmes (mean differences 23 and 37 days; p < 0.001 in both trials; 95% CIs not reported). Conclusions. Evidence from the included trials suggests that the NHE-based programmes can support prevention strategies, with several studies reporting improvements in eccentric strength and muscle architecture, and that the Askling L-Protocol is supported primarily by rehabilitation trials reporting shorter return-to-sport times. Overall, these findings indicate that the two protocols may serve different clinical purposes and should be selected according to the athlete’s stage on the injury continuum.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
