It is suggested that psychological factors such as personality characteristics, history of stressors, and coping resources can influence injury occurrence.1 For example, a player with a high trait anxiety who has experienced a recent life event and has poor coping resources will be more likely to perceive a sport specific situation as stressful. This may result in greater muscle tension and narrowing of the visual field.1 In team sports, this may cause players to be unable to avoid an opponent quickly or see the opponent in time, resulting in a higher risk to sustain an acute injury.2 This highlights the importance of exploring the role of psychological factors in relation to acute injuries.
Empirical research supports the relation between these psychological factors on injury risk, especially acute injuries.3–6 In these studies, potential psychological risk factors were measured at the start of a season with injury follow-up ranging from 3 months5,7,8 to 2 years.3 Personality characteristics, history of stressors, and coping resources explained 7% to 24% of the variance in injury occurrence.3–5,9 A more regular monitoring may increase this explained variance because stress levels can change on a day-to-day basis. Previous studies either measured potential psychological risk factors at the start of the season or monitored daily stressors on a weekly basis over a 13-week period.4,5,8 Higher baseline levels in perceived stress and a smaller decrease in perceived stress over this period was shown in injured players compared with healthy players.8 Monitoring perceived stress more regularly over a longer duration, for example an entire season, may provide more insight in the individual changes in stress in relation to acute injury occurrence.
The model of Andersen and Williams2 and most studies until now have focused on acute injuries,3–5,9 whereas overuse injuries also account for about 14% of the total injuries10,11 and are most predominant in sports involving repetition of movement patterns like jumping.12 Based on the theoretical framework of Kenttä and Hassmén,13 it can be assumed that a balance between stress and recovery is also important in reducing overuse injury risk. It is suggested that stress can result in a greater muscle tension,2 whereas a continuous greater muscle tension reduces the recovery potential and can in turn increase the risk of overuse injuries.14 Studies differentiating between acute and overuse injuries in relation to perceived stress and recovery are limited and found no difference in changes in perceived stress or recovery between acute and overuse injuries.15 This may be due to the monthly administering of the Recovery–Stress Questionnaire for Athletes (RESTQ-Sport)16 while changes may occur more rapidly. Monitoring changes in perceived stress and recovery more frequently over the course of a season may provide insight in relation to overuse injury occurrence.
Aforementioned studies mainly focused on stressors,3–5,9 more recent insights show the importance of recovery in counterbalancing stress for preventing injuries.8,15,17,18 Before an injury, players showed not only less recovery at baseline but also a greater decrease in recovery over time in comparison with healthy players.8,15 This implies that monitoring of recovery in relation to injury occurrence should be included. The Recovery–Stress Questionnaire for Athletes (RESTQ-Sport) is a state oriented questionnaire and developed to show changes in perceptions of stress and recovery of players over time.16 This questionnaire is a reliable and valid tool to monitor changes in both general and sport-specific stress and recovery over a period ranging from 3 days to 4 weeks.16 Regular monitoring with the RESTQ-Sport may provide insight in the changes in perceived stress and recovery over the course of a season. An increase in stress and/or decrease in recovery can warn players who are at risk and proper prevention strategies can be implemented.
Until now, research focusing on the role of psychological factors in injury occurrence have shown limited information about overuse injuries and lack information about recovery. The aim of this study is to investigate whether changes in perceived stress and recovery over the course of a season are risk factors for acute and overuse injuries in team sport players. It is hypothesized that team sport players show an increase in perceived stress and a decrease in perceived recovery before sustaining an injury. Differences between acute and overuse injuries are expected given the specific mechanisms.
A prospective nonexperimental cohort design was used to investigate changes in perceived stress and recovery in relation to injuries. In this study, 58 male (mean ± SD: age 22.1 ± 3.8 years, body mass 89.3 ± 10.9 kg, length 194.0 ± 7.8 cm) and 28 female (mean ± SD: age 21.5 ± 2.5 years, body mass 71.8 ± 10.9 kg, length 178.1 ± 8.1 cm) indoor team sport players participated. The participants played basketball (26), volleyball (38), or korfball (22) on an elite or a subelite level. Korfball is a mixed-gender team sport with 8 players in a team: 4 males and 4 females. The game has similarities with basketball and netball.10 The subelite level is defined as playing competition at the regional level, whereas elite level players compete at a national or an international level. All participants were fully informed about the study after which they signed an informed consent. Institutional approval was received from the medical ethical committee of the University Medical Center Groningen, the Netherlands. This study is part of a larger study known as the Groningen Monitoring Athletic Performance Study (Groningen MAPS).
Perceived Stress and Recovery
From the onset of the season, the players filled out the Dutch version of the RESTQ-Sport every 3 weeks,16,19 which showed sufficient reliability and validity.19 The RESTQ-Sport measures the frequency of current stress together with the frequency of recovery-related activities.16 In this study, a period of 3 weeks was chosen over which this frequency is measured in accordance with the periodization cycle of the players. The reliability of the RESTQ-Sport was supported for a recall period up to 4 weeks.16 The questionnaire consists of 77 items, including 1 warm-up question, referring to stress and recovery related activities during the previous 3 weeks. These items are scored on a Likert-type scale ranging from 0 (never) to 6 (always). The items can be divided into 19 scales: 12 general scales and 7 sport-specific scales. Each scale consists of 4 items. A more detailed description of the 19 scales can be found in the first chapter of the RESTQ-Sport manual.16 These scales can be subdivided into 4 main scores for General Stress, Sport Stress, General Recovery, and Sport Recovery. The main scores were calculated by taking the average of the scales.16
All injuries during the season were recorded by the team's physical therapist. The data collection system was based on the recommendations of Fuller et al.20 They defined an injury as “any physical complaint sustained by a player that results from a match or training, irrespective of the need for medical attention of time loss from sport activities”.20 In this study, the medical attention injuries were registered by the physical therapist and classified as acute or overuse injuries. An acute injury was defined as “an injury resulting from a specific, identifiable event.” The definition for an overuse injury was “an injury caused by repeated microtrauma without a single, identifiable event responsible for the injury.”20 The acute and overuse medical attention injuries were used for analysis in this study.
Out of the 86 team sport players participating in this study, 67 players were included in the 2011 to 2012 season and an additional 19 players were included in the 2012 to 2013 season. Players were monitored for a period of 41 weeks. Out of the 933 possible RESTQ-Sport questionnaires 97 (10.4%) were missing. Despite our efforts to help the players remember to fill out the questionnaires, the missing data were probably primarily due to players who refused or forgot to fill out the questionnaire. This left a total of 836 (89.6%) RESTQs for further analysis. The period between 2 RESTQs was marked as “healthy” or “before the injury”, according to the injury registration of the physical therapist. Players were injured in a total of 185 RESTQ periods. These periods were excluded from data analysis (22.1%), leaving 651 RESTQs for final data analysis. Each RESTQ refers to the previous 3-week period. An example is presented in Figure 1. For example, the player became injured in the period between RESTQ 7 and 8. The period before RESTQ 7 is the healthy period right before becoming injured and therefore marked as “before the injury”. The periods before RESTQ 4, 5, and 6 are marked “healthy”; RESTQ 8 and 9 were excluded from the analysis. The change scores in perceived stress and recovery for “healthy” and “before injury” periods were calculated for over 2 RESTQs administered 3 weeks (ΔRESTQ3wk) and 6 weeks apart (ΔRESTQ6wk)17 (Figure 1). For the entire season, ΔRESTQ3wk and ΔRESTQ6wk were related to “healthy” or “before injury” periods. These calculations were done for the 19 separate RESTQ-Sport scales.
Means and standard deviations were computed for the 4 main scores and 19 scales of the RESTQ-Sport over ΔRESTQ3wk and ΔRESTQ6wk. Data were analyzed using multinomial regression. The dependent variable was the marked period in which “healthy” was set as the reference category. Odds ratios and 95% confidence intervals (95%) over ΔRESTQ3wk and ΔRESTQ6wk were calculated for the “before injury” periods in comparison with the “healthy” periods. Regression models were made separately for acute injuries and overuse injuries with ΔRESTQ3wk and ΔRESTQ6wk as independent measure. IBM SPSS Statistics 20 for Windows was used for all data analysis. The level of statistical significance was set at P ≤ 0.05.
During the 41-week monitoring period, 68 players (79%) sustained a total of 128 injuries of which 66 (52%) were acute injuries and 62 (48%) were overuse injuries. The descriptive data of the absolute main scores on the RESTQ-Sport before an injury for players with an acute or overuse injury and healthy players are shown in Table 1. No significant differences were found between these groups on the absolute main RESTQ scores (P ≥ 0.05). The change scores of the 19 RESTQ-Sport scales were on average (range) 0.01 (−4.75-4.25) over ΔRESTQ3wk for healthy periods, −0.03 (−2.75-2.75) over ΔRESTQ3wk for before an acute injury, and −0.07 (−2.75-2.25) before an overuse injury. Over ΔRESTQ6wk the change scores of the scales were on average (range) −0.02 (−4.75-4.5) for healthy periods, −0.03 (−2.5-3) for periods before an acute injury, and −0.07 (−2-2) before an overuse injury.
The results for the multinomial logistic regression analysis for both acute and overuse injuries are shown in Table 2. No significant results were found for all main scores of the RESTQ. In ΔRESTQ3wk, no differences were shown before sustaining an acute injury in comparison with the healthy periods. However, a decrease on the scales Social Recovery, General Well-Being, and Disturbed Breaks over ΔRESTQ6wk increased the risk for acute injuries (ORs = 0.59, 0.61, 0.55, respectively, P ≤ 0.05). The ΔRESTQ6wk of the 19 RESTQ-Sport scales of periods before sustaining an acute injury in comparison with healthy periods are illustrated in Figure 2. When looking at overuse injuries a decrease in perceived Personal Accomplishment (−1.75-1) over ΔRESTQ3wk increased the risk to sustain an overuse injury (OR = 0.59, P ≤ 0.05). No changes over ΔRESTQ6wk were shown in players before an overuse injury in comparison with the healthy players.
In this study, changes in perceived stress and recovery over the course of a season were investigated as a potential risk factor for acute and overuse injuries in team sport players. It was hypothesized that players perceive more stress and less recovery before sustaining an injury. Furthermore, differences were expected for acute and overuse injuries given their specific mechanisms. The results show that there was indeed a higher risk with decreased recovery but not with increased stress. More specifically, perceived General Recovery decreased in the 6-week period before an acute injury compared with healthy periods. Risk of overuse injuries increased when perceived Sport Recovery decreased in the 3-week period before the injury compared with healthy periods. This highlights the importance of monitoring recovery in relation to injury risk.
As hypothesized, the relation between recovery and injury risk differed for acute and overuse injuries. This may be explained by different mechanisms of these types of injuries. Players scoring high on the General Recovery scales, Social Recovery and General Well-being are having frequent pleasurable contacts, relaxation, and amusement, next to having a good mood and feeling content.16 When the frequency of these recovery-related activities decreases, the current stress cannot be counterbalanced.18 This could lead to a larger stress response which may cause narrowing of the visual field and increase reaction time that can increase acute injury risk.2,16 On the contrary, decreased Sport Recovery, specifically decreased Personal Accomplishment, refers to the perception of feeling less integrated in the team, being less able to accomplish worthwhile things in sport, and less enjoying their sport.16 Questions in the RESTQ-Sport from this scale are more directly related to feeling fit and therefore more related to the development of overuse injuries. In the development of overuse injuries, pain symptoms appear gradually, consequently players will persist in training routines and game playing.12 Ultimately, this can lead to inadequate recovery and result in an overuse injury. However, more research is needed to clarify these mechanisms.
The time periods over which changes in recovery are observed differed between acute and overuse injuries. For acute injury risk, General Recovery decreased over a 6-week period before injury, whereas for overuse injuries, Sport Recovery decreased over a 3-week period before injury in comparison with the same healthy periods. The decreased perceived Sport Recovery in overuse injuries may be due to the symptoms appearing gradually and players persisting in their training routine. To the best of our knowledge, this is the first study, including different time periods before injury in relation to both acute and overuse injuries. This is important because it is not known over what time frame changes are reflected in perceived stress and recovery. This can be important, especially for overuse injuries that evolve over time.12 The lack of studies, including different time periods makes it hard to compare our results with previous studies. Studies of Fawkner et al7 and Ivarsson et al8 did show an increase in perceived stress over 2-weeks before injury, but did not include recovery and did not differentiate between acute and overuse injuries. These results together emphasize the importance of monitoring regularly over an entire season and study the effect of different time periods in relation to injury risk.
In line with the study of Ivarsson et al,8 our players showed a decrease in perceived Social Recovery, General Well-Being, and Personal Accomplishment over 3 and 6 weeks before injury. These scales are all part of the General Recovery main score. However, recovery is not included in the theoretical model of Andersen and Williams.1,21 Recovery, in terms of having a good time, being in a good mood, and dealing with emotional problems, could be a valuable addition to the model based on our results and the results of Ivarsson et al8 Both perceived stress and recovery change on a day-to-day basis affected by personality, (history of) stressors, and coping. In comparison with the study of Ivarsson et al,8 our study measured over a longer period and calculated change scores of perceived stress and recovery over 3-week and 6-week periods. This sheds light on the impact of changes in perceived stress and recovery in relation to acute and overuse injuries over a longer period of time. It may be interesting for future research to focus on changes over the different seasonal phases.
One of the strengths of this study is the incorporation of both perceived stress and recovery in relation to acute and overuse injuries. Furthermore, change scores were calculated to get insight in individual changes over time. A possible limitation may be that with the calculation of the 6-week change scores over a period of 3 weeks (1 RESTQ) in between isn't included; however, this is one of the first studies including such a method. Because stress and recovery can change on a day-to-day basis, another potential limitation is that the questionnaires were administered on a 3-week basis. This may affect the reliability, especially of the scales that have shown fluctuations in internal consistency, such as Lack of Energy, Physical Recovery, and Disturbed Breaks.16 This may also be an explanation for the contradictory finding that decreased perceived Disturbed Breaks increased injury risk in our study. However, with monitoring over an entire season we aimed to minimize the burden for players and optimize compliance. As a result, we were able to gather 836 questionnaires, missing only 10%, indicating a high compliance. This illustrates that our approach is suitable to be implemented in sports practice and that 3-week monitoring over an entire season can give insight in injury risk. Also a step forward was made in using a more individual approach by assessing changes in perceived stress and recovery. Finally the focus in our study was on players' perceived stress and recovery before sustaining an injury. However, other studies have shown that injured players also have more perceived stress and less perceived recovery compared with healthy players.22,23 Future research should also look at the perceived stress and recovery during an injury, which may give guidance for return to play interventions.
To conclude, decreased perceived recovery over both 3 and 6 weeks may suggest increased injury risk. Decreased General Recovery over a 6-week period was shown before an acute injury, whereas decreased Sport Recovery over a 3-week period was shown before an overuse injury. This indicates that, especially the recovery-enhancing practices, such as time with friends, amusement, and team building can be important, whereas the perceived stress of players doesn't seem to affect injury risk.
The results from this study indicate that the sports medical staff could carefully monitor changes in perceived recovery of team sport players as a possible tool to guide individual intervention strategies to reduce injury risk. More insight in both acute and overuse mechanisms in relation to perceived recovery may give clear guidance for individual or team recovery-related interventions to prevent these injuries.
The authors would like to thank the players, coaches, physical therapists, and student team-managers of the volleyball, basketball, and korfball teams participating in Groningen MAPS for their participation and commitment during the 2011 to 2012 and 2012 to 2013 seasons. Additionally, they would like to thank Marijke Pots, Marit Dopheide, and Nienke Schaap for collecting and processing the injury registration from the teams.
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Keywords:Copyright © 2017 Wolters Kluwer Health, Inc. All rights reserved.
RESTQ-Sport; acute injury; overuse injury; psychosocial stress and recovery