title: Heart rate-based training intensity and its impact on injury incidence among elite-level professional soccer players.
abstract: Elite-level professional soccer players are suggested to have increased physical, technical, tactical, and psychological capabilities when compared with their subelite counterparts. Ensuring these players remain at the elite level generally involves training many different bodily systems to a high intensity or level within a short duration. This study aimed to examine whether an increase in training volume at high-intensity levels was related to injury incidence, or increased the odds of sustaining an injury. Training intensity was monitored through time spent in high-intensity (T-HI) and very high-intensity (T-VHI) zones of 85-<90% and ≥90% of maximal heart rate (HRmax), and all injuries were recorded over 2 consecutive seasons. Twenty-three, elite professional male soccer players (mean ± SD age, 25.6 ± 4.6 years; stature, 181.8 ± 6.8 cm; and body mass, 79.3 ± 8.1 kg) were studied throughout the 2-years span of the investigation. The results showed a mean total injury incidence of 18.8 (95% confidence interval [CI], 14.7-22.9) injuries per 1,000 hours of exposure. Significant correlations were found between training volume at T-HI and injury incidence (r = 0.57, p = 0.005). Further analysis revealed how players achieving more time in the T-VHI zone during training increased the odds of sustaining a match injury (odds ratio = 1.87; 95% CI, 1.12-3.12, p = 0.02) but did not increase the odds of sustaining a training injury. Reducing the number of competitive match injuries among elite-level professional players may be possible if greater focus is placed on the training intensity and volume over a period of time ensuring the potential reduction of fatigue or overuse injuries. In addition, it is important to understand the optimal training load at which adaptation occurs without raising the risk of injury.
authors.affiliation: 1Servette Football Club, Center for Football Research, Geneva, Switzerland; 2Center of Sports Research and Innovation, Claude Bernard University Lyon.1, Lyon, France; 3Center for Sport Health and Exercise Research, Staffordshire University, Stafford, United Kingdom; 4Human Performance Laboratory, Technological and Higher Education Institute of Hong Kong, Hong Kong, China; 5Medical Center Excellence FIFA, Santy Orthopedicae Clinical, Lyon, France; and 6Athlete Health and Performance Research Center, ASPETAR, Qatar Orthopaedic and Sports Medicine Hospital, Doha, Qatar.
authors.forename: Adam L
authors.initials: AL
authors.lastname: Owen
authors.forename: Jacky J
authors.initials: JJ
authors.lastname: Forsyth
authors.forename: Del P
authors.initials: del P
authors.lastname: Wong
authors.forename: Alexandre
authors.initials: A
authors.lastname: Dellal
authors.forename: Sean P
authors.initials: SP
authors.lastname: Connelly
authors.forename: Karim
authors.initials: K
authors.lastname: Chamari
mesh_terms: D000328:Adult; D001265:Athletic Injuries / Q000453:epidemiology / Q000517:prevention & control; D012090:Cumulative Trauma Disorders / Q000517:prevention & control; D006339:Heart Rate; D006801:Humans; D015994:Incidence; D008297:Male; D009141:Musculoskeletal System / Q000293:injuries*; D064797:Physical Conditioning, Human / Q000009:adverse effects / Q000379:methods* / Q000502:physiology*; D012916:Soccer / Q000293:injuries*; D013997:Time Factors; D055815:Young Adult