Why Flexibility Deserves to Be Further Considered as a Standard Component of Physical Fitness: A Narrative Review of Existing Insights from Static Stretching Study Interventions

The utility of flexibility as a standard component of physical fitness has recently been questioned, sparking a heated debate among scientists. More specifically, it has recently been proposed to retire flexibility as a major component of physical fitness and as a result de-emphasis stretching from exercise prescriptions. The aim of this narrative review was to summarize and discuss the most recent evidence related to the chronic effects of static stretching (SS) on muscle strength, muscle power, muscle hypertrophy, and injury prevention in healthy individuals. A literature search was conducted using the electronic databases PubMed, SPORTDiscus, Web of Science, and Google Scholar up to November 2022. We only considered studies written in English that addressed the chronic effects of SS exercises on flexibility, muscle strength, muscle power, muscle hypertrophy, or injury prevention in healthy individuals. With reference to the existing knowledge, we concluded that flexibility deserves to be further considered as a standard component of physical fitness. This is based on the findings that in addition to flexibility, long-term SS training induces positive effects on muscle strength, muscle power, and muscle hypertrophy, irrespective of age and sex. There are also indications that long-term SS training could mitigate the risk of injury, although this remains a debatable topic. Furthermore, promising evidence shows that combining resistance training with SS exercises constitutes an effective approach benefiting muscle strength and hypertrophy more than resistance training alone. In conclusion, we would not support the recent suggestion that flexibility should be retired as a standard component of physical fitness and we would advocate for a continuous emphasis on the prescription of stretching exercises.