Introduction: Resistance training improves muscle strength, and static stretching increases
the range of motion. Due to the similarity in some mechanisms of both types of exercise, it
is possible that static stretching can also increase muscle strength, and resistance training
can improve flexibility, however the supporting evidence remains limited. Mechanical load
induced by muscle contraction or stretching triggers changes in cellular signaling, gene
expression, and alterations in the physiological, structural, and contractile properties of
muscle fibers, positively affecting muscle strength. Since resistance training can be defined
as dynamic stretching with additional load, the mechanical and neurological adaptations
necessary for increasing flexibility may also occur through resistance training. Purpose: The
aim of this literature review is to compare the effects of resistance training and static
stretching on muscle strength and flexibility. Methods: A literature search was conducted
in the PubMed database using a combination of keywords: resistance training AND
stretching AND (range of motion OR flexibility) AND strength. Studies included were
relevant, written in English, and not older than 15 years. Results: Considering the inclusion
and exclusion criteria, six studies were included in the review. Comparable increases in
muscle strength were observed in four studies in both the resistance training and static
stretching groups, while in two studies, the static stretching group did not exhibit statistically
significant improvements in muscle strength. In five studies, no statistically significant
differences were found in flexibility gains between the resistance training and static
stretching groups, whereas in one study, the resistance training group showed no statistically
significant changes in flexibility. Three studies reported simultaneous increases in muscle
strength and flexibility without statistically significant differences between the intervention
groups. Discussion and conclusion: Static stretching can increase muscle strength if the
weekly volume of stretching exercise is sufficiently high. Resistance training can be used to
improve flexibility, but it must be performed through a full range of motion. Unlike static
stretching, resistance training also has positive effects on the cardiovascular system and bone
mass, which means that individuals with limited time might consider performing only
resistance training.
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