Background information
Training with free weights or machines? That is the question here
by Claudio Viecelli
Myth busting: does strength training really reduce mobility?
11.6.2025
Translation: Elicia Payne
Strength training is much more than just muscle gain. It’s like medicine for your body, as it can help prolong a healthy life expectancy [1–6]. In this series we take a critical look at widespread myths. The topic of focus here is mobility and strength training.
The mobility of a joint is the angle by which it can move from its resting position to the outermost point of its movement in any direction [7]. This definition describes the ability of a joint or muscle group to move through its entire range of motion without restriction.
For decades now, stretching has been established as a strategy or training method to increase or maintain flexibility. What’s more, the effectiveness of stretching to increase mobility has been scientifically proven [8–11].Strength training, on the other hand, is often said to reduce mobility. But is that true? How does strength training influence mobility?
What stretching does and how it works?
There are various forms of stretching including static and ballistic stretching as well as proprioceptive neuromuscular facilitation (PNF). The most common is static stretching. It involves holding a stretching position for a certain period of time (e.g. 30 s) to increase flexibility. Ballistic stretching uses sweeping, bouncy movements to stretch the muscles beyond their normal range of motion, while PNF improves stretch tolerance and flexibility by alternately tensing and relaxing the muscles.
Researchers have defined two concepts that explain how stretching improves flexibility. The first idea, the mechanical theory [12], states that the properties of muscles and tendons change. The second concept, the sensory theory [13,14], explains that the body can withstand more stretch, i.e. the tolerance to stretch increases [15].
Stretching increases stretch tolerance and reduces muscle stiffness
Blazevich et al [16] investigated the effects of three weeks of static calf stretching on mobility, muscle and nerve function. 22 men were randomly assigned to a stretching group (n=12) or a control group (n=10). The stretching group performed calf stretches twice a day (4 × 30 s). The control group did nothing. Measurements of mobility, muscle activity, nerve reflexes and muscle structure were taken before and after the three weeks.
The results indicate that the improved mobility was due to increased stretch tolerance, increased muscle fibre length and reduced muscle stiffness, as no changes in muscle activation or tendon properties were observed.
Stretching increases mobility regardless of the method
Konrad, Stafilidis and Tilp [8] analysed the acute effects of static and ballistic stretching as well as PNF on the muscle and tendon properties of the lower leg. 122 test subjects were randomly divided into four groups: static, ballistic and PNF stretching as well as a control group. Various parameters were measured before and after a 4 × 30 second stretching session.
The study showed that all three stretching methods led to a significant increase in mobility (static: +4.3%, ballistic: +4.5%, PNF: +3.5%). At the same time, stretching led to a reduction in passive joint torque as well as muscle and muscle-tendon stiffness. Only PNF stretching reduced the maximum force development by 4.6%. Individual stretching, regardless of the method, therefore increases flexibility and reduces muscle stiffness.
Neuronal aspects are also important
Neuronal aspects also seem to play a role. Both acute and chronic stretching lead to an increase in mobility, but with neuronal control and reflex activity working in different ways. Acute stretching reduces the irritability of the spinal reflexes, which leads to a reduction in muscle tension and therefore enables a short-term improvement in mobility. Chronic stretching, on the other hand, reduces tonic reflex activity, which increases mobility [14].
Stretching therefore increases mobility. The corresponding mechanisms involve an increase in stretch tolerance and a reduction in muscle stiffness as well as neuronal aspects.
And what about strength training and mobility?
Stretching isn’t the only way to improve mobility. Strength training can also do this.
A recently published systematic review and meta-analysis [17], which included 55 studies, provides interesting findings on the effect of strength training on our mobility. If you train with weights, on fitness equipment or do Pilates, you can significantly improve your mobility.
The positive effects of strength training were comparable to those of classic stretching exercises. A combination of both training methods also showed similar results to stretching alone. What’s particularly good is that people who had previously done little sport benefited most from strength training – their mobility improved more than twice as much as people who were already active in sport.
The gender of the participants and the type of muscle tension didn’t play a significant role in the results. The age of the exercisers and the duration and frequency of the training also had no significant influence on the improvement in mobility. The study concluded that stretching before or after training isn’t absolutely necessary, as strength training already increases flexibility.
Other systematic reviews and meta-analyses show similar results [18,19]. Strength training, when performed over the full range of motion, doesn’t reduce mobility. It can, in fact, increase it.
References
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