Emerging evidence has suggested that short muscle-fibre lengths can increase the risk of hamstring injury

Hamstring injuries have long been the most common non-contact injury across the board in elite-level sport. And, despite much research into the causes and triggers, the rates continue to rise.

Emerging evidence has suggested that short muscle-fibre lengths can increase the risk of hamstring injury and an investigation by the American College of Sports Medicine has looked at the effects of training interventions with either lengthening or shortening muscle contractions on hamstring problems.

For the trial, 28 healthy males trained three times a week for six weeks and, after a four-week break, had a reassessment.

Results showed that those who trained with exercises that lengthened muscle contractions, such as the Nordic Hamstring Curl (above), saw an increase in muscle-fibre length within 14 days, with a loss of any gains following the four-week break.

Moves with shortening contractions saw a rapid reduction in fibre length, with no changes following the four-week break.

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