Reliability of a novel dynamic test of postural stability in high-level soccer players

Dynamic postural control in women athletes with and without nonspecific low back pain with high and low pain-related anxiety- A case-control study

BACKGROUND

Low back pain is common among athletes and it has been shown that postural control is altered in the general population with nonspecific low back pain (NSLBP). Psychological factors may also predispose individuals to risk of altered postural control. Dynamic postural control is essential to the performance of athletes. This study aimed to compare the dynamic postural control between women athletes with and without NSLBP with high and low pain-related anxiety.

METHODS

Forty-five female athletes (15 NSLBP with high pain-related anxiety, 15 NSLBP with low pain-related anxiety, and 15 healthy (control)) were included. Pain-related anxiety was assessed using the Pain Anxiety Symptom Scale-20 (PASS-20). Based on the cut-off score of 30 for the total score of PASS-20, NSLBP patients were classified into two groups of low and high pain-related anxiety. Participants performed double-leg vertical drop jump (DVJ) and single-leg vertical jump (SVJ) tests on a Kistler force plate (type 9260AA6, Kistler Instruments Inc, Switzerland). The total root mean square (RMS) of the center of pressure (COP), COP displacement in the anteroposterior (AP), and mediolateral (ML) directions, COP mean velocity, and time to stabilization (TTS) in vertical, AP, and total directions were extracted from COP and ground reaction force data using MATLAB software. One-way Analysis of variance (ANOVA) and Welch's ANOVA were employed to compare the groups. In case of significant findings, post hoc tests were performed.

RESULTS

The results showed that during DJV, athletes with high pain-related anxiety had significantly greater TTS in all total, AP, and ML directions than other groups (P < 0.05). Also, the control group showed greater total RMS distance during DJV than either NSLBP group. However, no significant differences in TTS and COP parameters were found between the groups during SVJ (P > 0.05).

CONCLUSIONS

The findings suggest that pain-related anxiety may contribute to athletes' postural control strategies. Therefore, it is important to consider the level of pain-related anxiety during planning postural control exercises for women athletes with NSLBP.

The effect of cryotherapy on postural stabilization assessed by standardized horizontal perturbations of a movable platform

BACKGROUND

Cryotherapy is a frequently used therapy in the acute treatment of sports injuries, although it has possible negative effects on dynamic postural stabilization.

RESEARCH QUESTION

What is the effect of cryotherapy on the postural stabilization assessed by imposed platform perturbations?

METHODS

Twenty-four healthy participants (15 male, 9 female) performed 2 test sessions (before and after cryotherapy) consisting of 4 trials each. Each trial included 30 s single leg stance (SLS) on both legs and 4 testing blocks (2 for each leg) of 30 s for the dynamic testing. A single testing block comprised 4 perturbations. After the first session, cryotherapy was applied to the right leg by placing it in ice water at a temperature between 10 °C and 12 ° for 20 min.

OUTCOME MEASURES

We assessed the Center of Pressure speed (CoPs) and the mean force variation for both static and dynamic tests. Additionally, the Time To Stability (TTS) was calculated for the perturbations.

RESULTS

In the static trials there was an interaction between leg and session present for the mean force variation (p = 0.01) with a large η² of 0.24, which shows higher variation of vertical force after application of the cryotherapy on the right leg. During the dynamic trials we found an interaction between leg and session for the TTS suggesting increase of the TTS due to the cryotherapy (p = 0.04), with a large η² of 0.17. No interaction effect was present for the CoPs in the mediolateral and anteroposterior direction (p = 0.62 and p = 0.12, respectively).

SIGNIFICANCE

Cryotherapy applied to the lower extremity results in a worse postural stabilization when assessed by platform perturbations. This might be the result of an altered balance strategy, due to impaired proprioception from the affected body part. More research is needed to examine the duration of this effect.

LEVEL OF EVIDENCE

Level 3, associative study.

Reliability of a Qualitative Instrument to Assess High-Risk Mechanisms during a 90° Change of Direction in Female Football Players

Sidestep cuts between 60° and 180° and one-leg landings have been identified as the main mechanisms of ACL injuries in several sports. This study sought to determine intra- and inter-rater reliability of a qualitative tool to assess high-risk movements in a 90° change of direction when the test is applied in a real framework of sport practice. Female footballers from two teams (n = 38) participated in this study and were asked to perform 90° cutting trials to each side, which were simultaneously filmed from a frontal and a sagittal view. A total of 61 cases were selected for 2D qualitative observational analysis by three raters. Poor reliability was found among each pair of raters as well as moderate reliability when the Cutting Movement Assessment Score (CMAS) was given by the same rater at different moments, but with too high a minimum detectable change. On the other hand, raters presented a significant, as well as moderate-to-good intra-rater reliability for most items of the CMAS tool. There was, however, non-significant reliability between observers in rating most check-points of the tool. For these reasons, more objective guidelines and clearer definitions for each criterion within the CMAS, as well as a longer, standardised training period for novel observers, would be highly recommended to improve the reliability of this tool in an applied context with female footballers.