5A 108 CHAPTER 5A workload) compared with a four week workload (chronic workload) is reported [14]. There’s a discussion whether RA or exponentially weighted moving averages (EWMA) are more suitable to use in the acute:chronic ratio [15], [16]. Itis found in elite Australian Football that EWMA in higher ratio’s (>2.0) may be a more sensitive indicator [14], [15]. Although both RA and EWMA correctly identify increased injury risk [14], [15]. In the afore mentioned studies in team sports[8]–[13] the calculation of acute and chronic workloads were mathematically coupled, i.e., the acute workload is contained in the chronic workload, and are spuriously correlated [17]. A solution is to uncouple i.e. the acute workload is not included in the chronic workload [17]. However in practice both coupled and uncoupled lead to the same results [18]. Many studies take measures of external and internal workload, into account in the calculation of the acute:chronic ratio [11], [12], [19]. While external workload defined as the work completed independently of internal characteristics [20] (i.e. duration, distance, number of throws, speed) is significant in comprehending the physical effort of the athlete, the internal workload, or the relative physiological and psychological stress is essential in determining the workload [21]. Foster et al. (2001) proposed a monitoring tool for training load based on rating of perceived exertion (RPE) [22]. This method, known as session-RPE method (sRPE), takes into account both the intensity and the duration [22]. The combination of intensity and duration is sRPE is a valid stand-alone tool for both training and competition to calculate the workload [22], [23]. Although applying sRPE in combination with the acute:chronic workload ratio (ACWR) may be promising for identification of the impact of workload on injury risk [24], there is an absence of studies that relates sRPE based ACWR with injury risk in running. Previous studies in running on workload and injury risk defined workload as a single nonrelative factor, like duration, distance or frequency [6], [7], [11]. The aim of the present study is to investigate the sRPE based acute workload, chronic workload, ACWR, and week-to-week and fortnightly ACWR difference as modifiable risk factors, in relation to injury risk of competitive runners. 2. MATERIALS AND METHODS 2.1. Participants A group of 23 competitive runners (16 male, 7 female) of the same training group and the same coach participated in the study during a period of 24 months. The runners competed in race distances of 800 meters to marathon on regional (5 runners), national (15 runners), and international (3 runners) level. Table 1 shows the runners’ baseline characteristics. Written informed consent was obtained from all individual runners participating in the study. The ethics committee of University Medical Center Groningen, the Netherlands (METc 2011/186), approved the research protocols.
RkJQdWJsaXNoZXIy MjY0ODMw