Ziga Kozinc, Nejc Sarabon
Running, as other physical activities, has many positive effects on health and well-being. Endurance running was shown to induce positive changes regarding body composition, resting heart rate, aerobic capacity and lipid profile (Hespanhol Junior et al., 2015). On the other hand, runners are at relatively high risk for sustaining an injury, particularly for various overuse injuries. A survey of 4 385 male runners carried out back in 1984 showed that 45.8% of them have sustain an injury in previous year, with 14.2% requiring medical care (Marti et al., 1988). A more recent systematic review reported the incidence of lower extremity running injuries ranging from 19.4% to 79.3%, with knee being affected most often (van Gent et al., 2007). Videbaek et al. (2015) reported the incidences of 17.8 and 7.7 per 1000 hours of exposure in novice runners and recreational runners, respectively. Common running injuries include medial tibial stress syndrome, Achilles tendinopathy, patellar tendinopathy, plantar fasciitis, ankle sprain, iliotibial band syndrome and patellofemoral pain syndrome (Lopes et al., 2012). As running grows more and more popular every year, the knowledge of prevention strategies is as desired as ever.
Many risk factors for sustaining a running-related injury have been documented. In their review, Saragiotto et al. (2014) found previous injury to be the main predictor for future injuries. Others were weekly distance, weekly training frequency and increased Q-angle (the angle between femur and tibia). Even more risk factors are known for specific injuries. Newman et al. (2013) reported prior use of orthotics, fewer years of running experience female gender, previous history of medial tibial stress syndrome, increased body mass index and navicular drop to increase the risk for sustaining a medial tibial stress syndrome. Neal et al. (2016) found the association between patellofemoral pain and peak hip adduction and internal rotation, contralateral pelvic drop and reduced peak hip flexion. Goff and Crawford (2011) listed excessive foot pronation (pes planus), excessive running volume, high arch (pes cavus), leg length discrepancy, obesity, prolonged standing/walking occupations (e.g., military personnel), sedentary lifestyle and tightness of Achilles tendon and intrinsic foot muscles to contribute to plantar fasciitis development. Regarding Achilles tendinopathy, Rutland et al. (2010) reported several intrinsic (strength imbalances, postural malalignment, lack of strength and flexibility, limited dorsiflexion range of motion) and extrinsic (non-gradual training program, training surface, etc.) risk factors in their review.
One of the most comprehensive literature reviews on preventing running injuries to date is by Yeung et al. (2011). Focusing only on lower limb soft-tissue injuries, the only efficacious strategies were wearing a patellofem-oral brace for preventing anterior knee pain (two trials) and utilizing custom-made foot orthoses for reducing MTSS in military recruits. Craig et.al (2008), similarly found the use of "shock-absorbing" insoles as the only effective strategy for preventing medial tibial stress syndrome. Enke and Gallas (2012) focused on prevention and management of common running-related injuries and concluded that the knowledge in this area is very limited and recommended using individualized treatment instead of a generalized prevention program for now. Even footwear choice seems to have little effect on running-related injury risk (Knapik et al., 2014).
Running-related injuries are often serious enough to cause a cessation of training and were shown as the most frequent reason (31%) for abandoning running in study of cohort of runners. The main objective of our meta-analysis was to assess the current knowledge on two types of preventive interventions--movement therapy interventions and training-modification interventions, and provide recommendations for clinicians regarding preventive program design for runners and point out how researchers should approach the problem in the future.
An electronic search of the PubMed (MEDLINE), PEDro and Cochrane Central Register of Controlled Trials databases was performed in April 2017 for randomized controlled trials and prospective cohort studies, examining the associations between movement therapy interventions or training modifications and running-related injury risk. We imposed no date or language restriction. We used the following search terms: running injury prevention, running injury therapy, running injury incidence, running injury exercise and running injury risk. In the MEDLINE database, we used set operators to search with the following combination: running injury AND (prevention OR therapy OR exercise OR incidence OR risk OR rehabilitation). After the initial search, titles and abstracts were screened to identify potentially relevant articles. Afterwards, full texts were obtained and final selection was made upon reading those. Both authors carried out all steps of article collection independently. Potential disagreements between authors were resolved by discussion and additional revision.
Studies were included in the meta-analysis if they met the following criteria: a) the study design was a randomized controlled trial or prospective cohort study b) the study investigated the effects of either movement therapy intervention (stretching, any type of resistance training, balance/stability training, coordination training or combination of those) or training-modification intervention (manipulation of training volume, intensity and frequency or adding substitute training) on running-related injury incidence, c) study subjects had to be involved in running--professionally, recreationally or as a part of their job (military personnel), d) running-related injury incidence was reported.
Both authors carried out the data extraction independently. The total number of running-related injuries of lower-limb in experimental and control groups were the main outcomes and were extracted to be pooled into a meta-analysis (two separate analyses were carried out for either type of intervention). All articles contained a descriptive display of injury types; therefore, extraction of only running-related injuries was possible. Other data extracted included: authors, year of publication, participants' characteristics (mean age, gender and experience) and intervention characteristics (duration, type and volume).
Assessment of methodological quality of included studies
Both authors independently assessed risk of bias of included studies using the PEDro Scale, which was shown to provide a fairly reliable scores of methodological quality of randomized controlled trials (Maher et al., 2003). A point was awarded for each of 11 criteria if it was clearly satisfied. Potential disagreements between authors were resolved by discussion and additional revision.
I-squared ([I.sup.2]) test and chi-squared ([Chi.sup.2]) test scores were calculated to assess the statistical heterogeneity among studies. For [I.sup.2] interpretation, we used the following criteria: 0% to 40% is considered low heterogeneity; 30% to 60% may represent moderate heterogeneity; 50% to 90% may represent substantial heterogeneity; 75% to 100% indicates considerable heterogeneity. Results for [Chi.sup.2] were considered statistically significant at p
Both meta-analyses were conducted using a random effect model (Mantel-Haenszel method). The difference in probability of injury occurrence between groups was expressed as relative risk (risk ratio), with entitled 95% confidence intervals. Heterogeneity assessment and effect size calculations were both performed with RevMan 5.3 (Review Manager, Version 5.3., Copenhagen: The Nordic Cochrane Centre, The Cochrane Collaboration, 2014).