Gender-specific psychosocial stressors influencing mental health among women elite and semielite athletes: a narrative review

Elite and semielite athletes commonly experience mental health concerns and disorders. Compared with men athletes, women athletes are at greater risk of a range of psychological stressors that contribute to health concerns and mental health disorders, which can impact their career satisfaction and longevity. In order to address and improve the mental health of women athletes, it is necessary to simultaneously tackle the gender specific psychosocial stressors that contribute to mental health outcomes. This narrative review examines the gender-specific stressors that affect mental health and well-being in women athletes, some of which are modifiable. Psychosocial stressors identified include exposure to violence, be it psychological, physical or sexual in nature, which can result in a myriad of acute and long-lasting symptoms; and inequities as reflected in pay disparities, under-representation in the media, fewer opportunities in leadership positions and implications associated with family planning and motherhood. Strategies to promote mental health in women athletes should be considered, and where possible, should proactively address gender-specific stressors likely to influence mental health in order to maximise positive outcomes in women athletes.

Multipotential stromal cells in the talus and distal tibia in ankle osteoarthritis - Presence, potency and relationships to subchondral bone changes

A large proportion of ankle osteoarthritis (OA) has an early onset and is post‐traumatic. Surgical interventions have low patient satisfaction and relatively poor clinical outcome, whereas joint‐preserving treatments, which rely on endogenous multipotential stromal cells (MSCs), result in suboptimal repair. This study investigates MSC presence and potency in OA‐affected talocrural osteochondral tissue. Bone volume fraction (BV/TV) changes for the loading region trabecular volume and subchondral bone plate (SBP) thickness in OA compared with healthy tissue were investigated using microcomputed tomography. CD271‐positive MSC topography was related to bone and cartilage damage in OA tissue, and in vitro MSC potency was compared with control healthy iliac crest (IC) MSCs. A 1.3‐ to 2.5‐fold SBP thickening was found in both OA talus and tibia, whereas BV/TV changes were depth‐dependent. MSCs were abundant in OA talus and tibia, with similar colony characteristics. Tibial and talar MSCs were tripotential, but talar MSCs had 10‐fold lower adipogenesis and twofold higher chondrogenesis than IC MSCs (P = .01 for both). Cartilage damage in both OA tibia and talus correlated with SBP thickening and CD271+ MSCs was 1.4‐ to twofold more concentrated near the SBP. This work shows multipotential MSCs are present in OA talocrural subchondral bone, with their topography suggesting ongoing involvement in SBP thickening. Potentially, biomechanical stimulation could augment the chondrogenic differentiation of MSCs for joint‐preserving treatments.

The wear of fixed and mobile bearing unicompartmental knee replacements

Unicompartmental knee replacements (UKR) are an option for surgical intervention for the treatment of single-compartment osteoarthritis. The aim of this study was to compare the wear of a low-conformity fixed-bearing UKR with a conforming mobile bearing UKR under two kinematic conditions, to investigate the effect of implant design and kinematics on wear performance in a physiological knee wear simulator. Under both sets of kinematic conditions, the relatively low-conforming fixed UKR showed lower wear, compared with the more conforming anterior-posterior sliding mobile bearing. However, it should be noted that differences in materials between the two designs also contribute to the relative wear performance of the bearings. The combined wear of the medial and lateral bearings of the fixed-bearing UKR as a ‘total knee’ were significantly reduced compared with a fixed-bearing total knee replacement studied under the same kinematic conditions.

Identifying athletes at risk of hamstring strains and how to protect them

1. One common soft-tissue injury in sports involving sprinting and kicking a ball is the hamstring strain. Strain injuries often occur while the contracting muscle is lengthened, an eccentric contraction. We have proposed that the microscopic damage to muscle fibres that routinely occurs after a period of unaccustomed eccentric exercise can lead to a more severe strain injury. 2. An indicator of susceptibility for the damage from eccentric exercise is the optimum angle for torque. When this is at a short muscle length, the muscle is more prone to eccentric damage. It is known that subjects most at risk of a hamstring strain have a previous history of hamstring strains. By means of isokinetic dynamometry, we have measured the optimum angle for torque for nine athletes with a history of unilateral hamstring strains. We also measured optimum angles for 18 athletes with no previous history of strain injuries. It was found that mean optimum angle in the previously injured muscles was at a significantly shorter length than for the uninjured muscles of the other leg and for muscles of both legs in the uninjured group. This result suggests that previously injured muscles are more prone to eccentric damage and, therefore, according to our hypothesis, more prone to strain injuries than uninjured muscles. 3. After a period of unaccustomed eccentric exercise, if the exercise is repeated 1 week later, there is much less evidence of damage because the muscle has undergone an adaptation process that protects it against further damage. We propose that for athletes considered at risk of a hamstring strain, as indicated by the optimum angle for torque, a regular programme of mild eccentric exercise should be undertaken. This approach seems to work because evidence from a group of athletes who have implemented such a programme shows a significant reduction in the incidence of hamstring strains.

Predicting Hamstring Strain Injury in Elite Athletes

INTRODUCTION

Eccentric exercise, where the contracting muscle is lengthened, produces microscopic damage in muscle fibers, and sensations of stiffness and soreness, the next day. These normally resolve within a week. A more major sports injury is the muscle strain. Because strain injuries are known to occur during eccentric contractions, it is hypothesized that the microscopic damage from eccentric exercise can, at times, progress to a muscle strain. As the amount of microscopic damage depends on the muscle's optimum length for active tension, it is further proposed that optimum length is a measure of susceptibility for muscle strains. The athletes most at risk of a hamstring strain are those with a previous history of such injuries. Here the prediction is tested that optimum lengths of previously injured hamstrings are shorter and therefore more prone to eccentric damage than uninjured muscles.

METHODS

Mean optimum angle for peak torque in a previously injured muscle of nine athletes with a history of unilateral hamstring strains was compared with the uninjured muscle of the other leg and with muscles of 18 uninjured athletes. Optimum angle was determined with isokinetic dynamometry.

RESULTS

In previously injured muscles, torque peaked at significantly shorter lengths than for uninjured muscles. Peak torque and quadriceps:hamstrings torque ratios were not significantly different.

CONCLUSIONS

The shorter optimum of previously injured muscles makes them more prone to damage from eccentric exercise than uninjured muscles and this may account for the high reinjury rate. The shorter optimum may reflect the muscle's preinjury state or be a consequence of the healing process. To reduce the incidence of strain injuries, it is recommended that a combined program of eccentric exercise and muscle testing be carried out.

The role of the length-tension curve in the control of movement

The length-tension curve of muscle is one of the important descriptors of mechanical performance, and also a direct reflection of the underlying structure, particularly the number of sarcomeres connected in series in muscle fibres. This number is one of the most plastic properties of muscle, changing within days after changes in activity patterns. We propose that this adaptation is to prevent eccentric contractions from occurring beyond the optimum length for tension generation, since this is the region of sarcomere instability and muscle damage. Evidence for this is presented for muscles from rats trained on a treadmill, and from motor units of the gastrocnemius muscle of the cat.

Damage to different motor units from active lengthening of the medial gastrocnemius muscle of the cat

Slow-twitch motor units in the medial gastrocnemius muscle of the anesthetized cat were found to have an average optimum length for active tension that was 0.8 +/- 0.5 (SE) mm longer than the whole muscle optimum. For fast-twitch units (time to peak < 50 ms), the average optimum was 1.3 +/- 0.3 mm shorter than the whole muscle optimum. After the muscle had been subjected to 10 stretches while maximally activated, beginning at the whole muscle optimum length, the optimum lengths of the 27 fast-twitch motor units shifted significantly further in the direction of longer muscle lengths (mean 4.3 +/- 0.3 mm) than for the eight slow-twitch units (2.1 +/- 0.4 mm). A shift in the muscle's length-tension relation was interpreted as being due to sarcomere disruption. Statistical analysis showed that a motor unit's optimum length for a contraction, relative to the whole muscle optimum, was a better indicator of the unit's susceptibility to damage from active lengthenings than was motor unit type.

Effect of eccentric muscle contractions on Golgi tendon organ responses to passive and active tension in the cat

To investigate the possibility of a peripheral contribution to the perturbations of force sensation reported to occur after eccentric exercise, responses to passive and active tension were recorded from Golgi tendon organs in the medial gastrocnemius muscle of the anaesthetised cat, before and after a series of eccentric contractions. After the eccentric contractions, nearly all tendon organs commenced firing at a shorter muscle length during slow passive stretch than before, probably because of a rise in whole muscle passive tension. There was a small drop in the sensitivity to incremental tension, but no mean change in tension threshold. Following the eccentric contractions, there was a small, but not significant, increase in tendon organ sensitivity to active tension, which was graded using a method of optimised, distributed stimulation of divided ventral roots. Sensitivity was estimated as the mean response over a range of tensions and as the change in discharge rate in response to incremental tension. The experiments provided the opportunity of comparing tendon organ sensitivities to graded passive and active whole muscle tension. In agreement with previous work in which whole muscle nerve stimulation was employed, little difference was found. It was concluded that the peripheral contribution to perturbations of force perception after eccentric exercise is likely to be small and that the centrally derived sense of effort plays the dominant role. Tendon organs appear to be remarkably reliable in signalling whole muscle tension, whether passive or active, and even after the muscle's force production has been disturbed by fatigue or eccentric exercise.

Human hamstring muscles adapt to eccentric exercise by changing optimum length

PURPOSE

It is now established that unaccustomed eccentric exercise leads to muscle fiber damage and to delayed-onset muscle soreness (DOMS) in the days after exercise. However, a second bout of eccentric exercise, a week after the first, produces much less damage and soreness. The purpose of this study was to provide evidence from muscle mechanical properties of a proposed mechanism for this training effect in human hamstring muscles.

METHODS

The eccentric exercise involved 12 sets of 6 repetition "hamstring lowers," performed on specially designed equipment. Hamstring angle-torque curves were constructed for each of 10 subjects (8 male and 2 female) while they performed maximum voluntary knee extension and flexion movements on an isokinetic dynamometer. Testing sessions were performed over the week before eccentric exercise, immediately post exercise, and daily, up to 8 d post exercise. Subject soreness ratings and leg girth measurements were also made post exercise. Six subjects performed a second bout of eccentric exercise, 8 d after the first, and measurements were continued up to 10 d beyond that.

RESULTS

There was a significant shift in the optimum angle for torque generation (Lo), to longer muscle lengths immediately post exercise (7.7 degrees +/- 2.1 degrees, P < 0.01), indicating an increase in series compliance within some muscle fibers. Subsequent measurements showed increases in leg girth and some muscle soreness, suggesting muscle damage. The shift in Lo persisted, even after other injury parameters had returned to normal, consistent with a training effect. Subjects also showed fewer signs of muscle damage after the second exercise bout.

CONCLUSION

This is the first study to show a sustained shift in optimum angle of human muscle as a protective strategy against injury from eccentric exercise. Implications of this work for athletes, particularly those prone to hamstring strains are discussed.