Breathing Techniques Affect Female but Not Male Hip Flexion Range of Motion

Hip Range of Motion During Passive and 1-Leg Exercises Is Greater in Women: A Meta-analysis and Systematic Review

PURPOSE

To summarize sex-related differences in hip range of motion (ROM), including flexion, extension, abduction, adduction, internal rotation, and external rotation.

METHODS

We performed a systematic search of 3 databases (PubMed, CINAHL [Cumulative Index to Nursing and Allied Health Literature], and Embase). The search terms were as follows: hip, pelvis, range of motion, kinematic, men, and women. Included studies reported sex-specific data on hip ROM in healthy, uninjured adults. To generate hip ROM mean differences, a DerSimonian-Laird random-effects model was used. Effect sizes were pooled for each exercise. Subgroup analyses compared hip ROM by physical activity group: passive ROM, 1-leg hop or jump, 2-leg hop or jump, 2-leg drop or landing, 1-leg squat, 2-leg squat, walking, and jogging/running. Positive effect sizes represent greater ROM in women.

RESULTS

Thirty-eight studies with 3,234 total subjects were included; of these subjects, 1,639 were women (50.1%). The mean age was 25.3 years. An effect difference was considered statistically significant if P < .05 and clinically significant if the mean difference was greater than 4.0°. Women showed statistically and clinically significantly greater hip flexion in passive ROM (mean difference, 6.4°) and during the 1-leg hop or jump exercise (mean difference, 6.5°). Women also showed statistically and clinically significantly greater hip adduction during the 1-leg hop or jump (mean difference, 4.5°) and 1-leg squat (mean difference, 4.4°) exercises, as well as statistically and clinically significantly greater hip internal rotation in passive ROM (mean difference, 8.2°). In contrast, men showed statistically and clinically significantly greater flexion during the 2-leg hop or jump exercise (mean difference, -9.1°). No clinically significant differences in extension, abduction, or external rotation were found between women and men.

CONCLUSIONS

On average, women showed statistically and clinically significantly greater flexion, adduction, and internal rotation during passive and 1-leg exercises whereas men showed statistically and clinically significantly greater flexion during the 2-leg hop or jump exercise.

LEVEL OF EVIDENCE

Level IV, meta-analysis and systematic review of Level II-IV studies.

The effects of slow breathing on postural muscles during standing perturbations in young adults

Maintaining standing balance is vital to completing activities in daily living. Recent findings suggest an interaction between cardiovascular and postural control systems. Volitional slow breathing can modulate the cardiovascular response and affect postural control during quiet standing. However, the effects of slow breathing during threats to standing balance have not been studied. The study examined the effect of slow breathing on the latency and amplitude of postural muscle responses to perturbations of the base of support in healthy, young adults. Twenty-seven participants completed two balance perturbation tasks in standing on an instrumented split-belt treadmill while breathing spontaneously and breathing at 6 breaths per minute. Each perturbation task consisted of 25 posteriorly directed translations of the treadmill belts every 8-12 s. Muscle latency and muscle burst amplitude were measured using surface electromyography from the right limb for the quadriceps (QUADS), medial hamstring (MH), gastrocnemii (GASTROC), soleus (SOL), and tibialis anterior (TA) muscle groups, while a respiratory belt was used to record respiratory rate. Results indicated that during the slow breathing task both muscle latency (p = 0.022) and muscle burst amplitude (p = 0.011) decreased compared to spontaneous breathing. The EMG pre-perturbation activation was not significantly different in any muscle group between conditions (p > 0.167). The study found that reducing respiratory rate to approximately 6 breaths per minute affects the neuromuscular responses in the lower limb muscles to perturbations.