Flexibility and Its Effects on Sports Injury and Performance
Key Results
Flexibility can be measured statically (end of range of motion), dynamic-passive (stiffness/compliance) or dynamic-active (muscle contracted); dynamic measures are less dependent on the subject's discomfort and more objective
Stretching produces acute and chronic flexibility changes, but it is hard to separate a change in stretch tolerance from a change in muscle stiffness; how flexibility is measured shapes the findings
There is no scientifically based prescription for flexibility training, and no conclusive statement can be made about flexibility and athletic injury: studies report opposing findings, often fail to distinguish strain, sprain and overuse injury, and rarely use exposure as the denominator
Basic science suggests active warm-up may protect against muscle strain injury, but clinical research is equivocal
Specific flexibility patterns are associated with specific sports and even positions; the flexibility-performance relationship is likely sport-dependent
Decreased flexibility has been associated with better running and walking economy; increased stiffness may aid isometric and concentric force generation, and elastic energy storage is best when muscle stiffness matches the movement frequency in stretch-shortening actions
Mechanism
Stiffness is not simply "bad": a stiffer muscle-tendon unit returns elastic energy more effectively when its stiffness matches the cadence of stretch-shortening movements, and transmits force better in isometric and concentric actions — which is why less flexible runners can be more economical. Inference, not in the abstract: an optimum flexibility level is therefore sport- and joint-specific rather than "more is better".
Practical Application
This 1997 narrative review finds no conclusive evidence that flexibility (or stretching) prevents sports injury and no science-based prescription for flexibility training; what it does find is that lower flexibility goes with better running and walking economy and that stiffness helps force production — so endurance athletes should not chase flexibility for its own sake
Flexibility needs are sport-specific: train the range your discipline requires, not a generic standard
Active warm-up may protect against muscle strain (basic-science evidence; clinical evidence equivocal) — a reason to warm up actively rather than to stretch statically before competing
Not from this paper; the base's own practice: for cycling, hip-flexor and hamstring range adequate for the pedalling position and a low riding posture; dynamic mobility before riding, static stretching (if wanted) after or in separate sessions — see Behm 2011 REF-284
Limitations
1997 review — many studies since then
Narrative format
Limited evidence base at time of publication
How this entry was checked and changed
Why this level
regraded 2026-09-27 from B: authoritative narrative review (McHugh/NISMAT group) without systematic method; "B" is not a review category in the rubric
Content correction 2026-09-27
"Poor flexibility → increased hamstring and adductor strain risk", "excessive flexibility → joint injury risk (hypermobility)" and the "U-shaped" flexibility-injury relationship are not in the abstract (which says no conclusive statement can be made) — removed.
Abstract's findings on measurement, stretch tolerance vs stiffness, economy and force generation added; "avoid static stretching pre-competition" relabelled as base practice.
Level B -> B+ (review category); Sport cycling -> general.