Assessment of the Maximal Range of Motion from Initial Sensation of Stretching to the Limits of Tolerance

摘要

The aim of this study was to determine whether the first sensation of stretching (ROM_(FSS)) may predict the maximum range of motion (ROM_(MAX)) in male (N = 37) and female (N = 32) volunteer subjects, and to assess the reliability of the ROM perceived by subjects in relation to a pre-determined ROM (ROM_(50%)). Subjects attempted three experimental sessions with 48 hours between sessions 1 and 2 and 28 days between sessions 1 and 3. Within each session, five trials were performed with isokinetic equipment to assess posterior thigh muscle flexibility. The results revealed a strong and significant correlation between ROM_(MAX) and ROM_(FSS) for both sexes, females ( r = 0.96, p < 0.001, R ~(2) = 0.92) and males ( r = 0.91, p < 0.001; R ~(2) = 0.82). The accuracy of the model verified by the standard error of estimate (SEE) was high in the equations proposed for both female (SEE = 4.53%) and male (SEE = 5.45%). Our results revealed that ROM_(FSS) may predict the ROM_(MAX) for both male and female subjects. The ROM_(FSS) may contribute to the development of evaluation methods that do not subject the individuals to conditions that may include unnecessary risk of injury and is well suited to monitor the training process of stretching exercises with submaximal loads.Key points An individual’s tolerance to stretching can be considered a continuum marked by the first sensation of stretching and the maximum range of motion as the continuum’s end-points.The first sensation of stretching and the point representing halfway between the first sensation and maximal range of motion are reliable measures in young men and women.The first sensation of stretching may be a safe and useful predictor of maximal range of motion. Key words: Prediction equation, range of motion, onset of pain, muscle stretch intensityIntroductionPredicting maximal performance from a submaximal effort in resistance training is a useful method to avoid exposure to extreme physical requirements, thereby minimizing the risks of injury (Mayhew et al. 2008). This approach uses muscle endurance performance through a number of repetitions performed to predict maximal strength performance, replacing a 1-repetition maximum protocol (Mayhew et al. 2008; Knutzen et al. 1999). These strength predictions also aid in exercise prescription and manipulation of training load (Mayhew et al. 2008). Unlike muscle strength, prediction equations currently do not exist for flexibility capacity represented by joint maximal range of motion (ROM_(MAX)). The ROM_(MAX) is defined as the maximum range of joint motion tolerated by the participant during a stretching maneuver (Halbertsma et al. 1996; Magnusson et al. 2000; Blazevich et al. 2012).While ROM_(MAX) is a variable associated with the maximal tolerance of the subject to stretching, another variable related to the individual's tolerance to stretching is the first sign of pain (i.e., first detection of pain), that was first analyzed by Halbertsma and G?eken (1994). In spite of the use of the term “pain”, the authors instructed the volunteers instead to note the first sensation of tension in the musculature, generated during passive stretching. A similar procedure was performed in other studies that also associated the first sensation of tension in the musculature during stretching to the individual's tolerance of stretching (Cabido et al. 2014; Halbertsma et al. 1999; 2001; Ylinen et al. 2009). In these studies, the ROM corresponding to the first muscular sensation of stretching (FSS) was the measure used (ROM_(FSS)). Afferent communication from the muscle-tendon unit (MTU) and joint kinesthetic receptors is responsible for the signaling of ROM_(MAX) and ROM_(FSS) by the individual during a stretching maneuver. The modulation of information by individual anatomical and physiological differences and, consequently, the impacts on ROM variables are currently not addressed in the literature. Some authors have reported that of the various putative neuromuscular factors, higher ROMS are associated with the individual's ability to tolerate higher torque values (Ben and Harvey 2010; Magnusson 1998; Weppler and Magnusson, 2010). According to Blazevich et al. (2012), this capacity and volitional stretch termination may be related to subconscious responses to afferent stretch (I and IIa), pressure (III) and pain (IV), as well as differences in the supraspinal registration of afferent signals. These authors also suggest that future studies are warranted to explain each responses relative influence on ROM.Considering the multi-factorial influences described above, ROM_(MAX) indicates the maximal tolerable stretching sensation and ROM_(FSS) represents the first sensation of stretching associated with MTU stretch-associated tension. Thus, ROM_(MAX) and ROM_(FSS) could represent the limits of a continuum of the individual's tolerance to stretching. Postulating the existence of this continuum is based on the results of studies that have a