Hamstring stretching exercises performed in the working place are effective for increasing hamstring muscle extensibility. This increase generates a more aligned thoracic curve and more anterior pelvic inclination when maximal trunk flexion is performed.

The study aims were to describe positional differences in the acceleration and sprint profiles of professional football players in match-play, and analyse start speeds required based on the intensity of accelerations and decelerations. This longitudinal study was conducted over thirteen competitive microcycles in a professional football team from LaLiga 123. Data were collected through electronic performance tracking systems. Every player was categorised based on the playing position: central defender (CD), fullback (FB), forward (FW), midfielder (MF), and wide midfielder (WMF). In respect of acceleration profile, positional differences were found for all variables (p < 0.05), except average magnitude of accelerations (ACC AVG , p = 0.56) and decelerations (DEC AVG , p = 0.76). The sprint profile also showed positional differences for all variables (p < 0.05), apart from sprint duration (p = 0.07). In addition, although low-intensity accelerations required significantly greater start speeds (Vo) than high-intensity accelerations in WMF (0.4 ± 0.2 km/h; p < 0.05) and FW (0.4 ± 0.2 km/h; p < 0.05), no significant differences (p > 0.05) were found in CD, FB, and MF. However, high-intensity decelerations were performed at significantly higher Vo than low-intensity decelerations in MF (2.65 ± 0.1 km/h; p < 0.05), FW (3.3 ± 0.1 km/h; p < 0.05), FB (3.9 ± 0.4 km/h; p < 0.05), WMF (4.3 ± 0.3 km/h; p < 0.05), and CD (4.1 ± 0.7 km/h; p < 0.05). Therefore, positional differences exist for most variables of the acceleration and sprint profiles. In addition, different Vo were observed between high-intensity and low-intensity accelerations as well as high-intensity and low-intensity decelerations.

The aims of this study were (a) to determine and compare the concurrent hamstring criterion-related validity of the sit-and-reach (SR) and toe-touch (TT) tests in different athletes (tennis players, kayakers, canoeists, and cyclists); (b) to determine the criterion-related validity of the pelvic tilt assessed by the Spinal Mouse system as a measure of hamstring flexibility in athletes; and (c) to evaluate the influence of spinal posture, pelvic tilt, and hamstring muscle flexibility in the SR and TT scores. Twenty-four tennis players, 30 canoeists, 43 kayakers, and 44 cyclists were recruited. Passive straight leg raise (PSLR), SR, and TT tests were randomly performed. Spinal curvatures and pelvic tilt were evaluated with a Spinal Mouse system when the maximal trunk flexion was achieved in the SR and TT tests. Tennis players and cyclists showed moderate correlations between PSLR with respect to SR (β = 0.78 and β = 0.76, respectively) and TT (β = 0.77 and β = 0.74, respectively). Correlations were slightly lower in canoeists (SR, β = 0.64; TT, β = 0.75). Kayakers showed the lowest correlation values (SR, β = 0.53; TT, β = 0.57). Correlation values between PSLR and pelvic tilt angle in both the SR and TT tests were β < 0.70 in all the groups of athletes. Stepwise multiple regression analysis showed a high variance explained from pelvic tilt and lumbar spine in the SR score. In conclusion, the SR and TT tests can be appropriate measures to determine spine flexibility and pelvic tilt range of motion but not to evaluate the hamstring muscle flexibility in tennis players, canoeists, kayakers, and cyclists.

The purpose of this study was to determine the influence of hamstring muscles extensibility in standing, maximal trunk flexion with knees extended and on the bicycle in lower handlebar-hands position of highly trained cyclists. Ninety-six cyclists were recruited for the study (mean ± SD, age: 30.36 ± 5.98 years). Sagittal spinal curvatures and pelvic tilt were measured in the standing position, maximal trunk flexion with knees extended (sit-and-reach test) and while sitting on a bicycle in lower handlebar-hand position using a Spinal Mouse system. Hamstring muscles extensibility was determined in both legs by passive straight leg raise test (PSLR). The sample was divided into three groups according to PSLR angle: (1) reduced extensibility (PSLR < 80º; n = 30), (2) moderate hamstring extensibility group (PSLR = 80º – 90º; n = 35), and (3) high hamstring extensibility (PSLR = > 90º; n = 31). ANOVA analysis showed significant differences among groups for thoracic (p < 0.001) and pelvic tilt (p < 0.001) angles in the sit-and-reach test. No differences were found between groups for standing and on the bicycle position. Post hoc analysis showed significant differences in all pairwise comparisons for thoracic angle (p < 0.01) and pelvic angle (p < 0.001) in the sit-and-reach test. No differences were found in lumbar angle in any posture. In conclusion, the hamstring muscles extensibility influence the thoracic and pelvic postures when maximal trunk flexion with knees extended is performed, but not when cyclists are seated on their bicycles

The aim of this study was to determine acute effects of hamstring stretching in thoracic and lumbar spinal curvatures and pelvic tilt. Fifty-five adults (29.24 ± 7.41 years) were recruited for this study. Subjects performed a hamstring stretching protocol consisting of four exercises. The session consisted of 3 sets of each exercise and subjects held the position for 20 seconds with a 30-second rest period between sets and exercises. Thoracic and lumbar spinal angles and pelvic tilt were measured with a SpinalMouse in relaxed standing, sit-and-reach test and Macrae & Wright position. Hamstring extensibility was determined by active straight leg raise test and sit-and-reach score. All measures were performed before and immediately after the hamstring stretching protocol. Active straight leg raise angle and sitand-reach score significantly improved immediately after the stretching protocol (p<0.001). Greater anterior pelvic tilt (p<0.001) and lumbar flexion (p<0.05) and a smaller thoracic kyphosis in the sit-and-reach (p<0.001) were found after the stretching protocol. However, stretching produced no significant change on spinal curvatures or pelvic tilt in standing and maximal trunk flexion with knees flexed. In conclusion, static stretching of the hamstring is associated to an immediate change in the sagittal spinal curvatures and pelvic position when performing trunk flexion with knees extended, so that allowing for greater lumbar flexion and anterior pelvic tilt and lower thoracic kyphosis. Hamstring stretching is recommended prior to sport activities involving trunk flexion with the knees straight.

The aim of this study was to systematically review the current literature on the electromyographic (EMG) activity of six core muscles (the rectus abdominis, the internal and external oblique, the transversus abdominis, the lumbar multifidus, and the erector spinae) during core physical fitness exercises in healthy adults. A systematic review of the literature was conducted on the Cochrane, EBSCO, PubMed, Scopus, and Web of Science electronic databases for studies from January 2012 to March 2020. The Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines were used. The inclusion criteria were as follows: (a) the full text available in English; (b) a cross-sectional or longitudinal (experimental or cohorts) study design; (c) the reporting of electromyographic activity as a percentage of maximum voluntary contraction (% MVIC), millivolts or microvolts; (d) an analysis of the rectus abdominis (RA), transversus abdominis (TA), lumbar multifidus (MUL), erector spinae (ES), and the internal (IO) or external oblique (EO); (e) an analysis of physical fitness exercises for core training; and (f) healthy adult participants. The main findings indicate that the greatest activity of the RA, EO, and ES muscles was found in free-weight exercises. The greatest IO activity was observed in core stability exercises, while traditional exercises showed the greatest MUL activation. However, a lack of research regarding TA activation during core physical fitness exercises was revealed, in addition to a lack of consistency between the studies when applying methods to measure EMG activity.

The posture adopted in cycling is not the only result of the higher thoracic curvature in cyclists when standing. It is necessary to include spinal postural awareness in the training plan and thoracic muscle resistance exercises that favour more aligned postures while standing.

The purpose of the study was: 1) to determine the intensity of an indoor cycling session; 2) to know the correlation between the rating of perceived exertion (RPE) scales (Borg and OMNI) and % heart rate reserve (%HRR) with categories; and 3) to evaluate the validity of RPE scales (Borg and OMNI) with respect to the heart rate (HR) and %HRR. A total of fifty-three subjects, 25 males and 28 females (ages: 28.79 ± 6.04 years; body height: 1.71 ± 0.09 m; body mass: 69.59 ± 13.69 kg) were recruited from a private fitness club. All subjects performed the same predesigned indoor cycling session with a total duration of 50 minutes. During the experimental trial, the HR was recorded every 5 s. The Borg 6–20 RPE and OMNI 0–10 scales were used to assess perceived exertion in each phase. The average HR in the cardiovascular phase was 152.24 ± 14.11 b•min-1, the %HRR was 80.62 ± 7.10; and the overall RPE (Borg and OMNI scales) was 14.94 ± 1.11 and 7.18 ± 0.79 points, respectively. The correlation between an average HR and %HRR with Borg and OMNI scales was lower than r = 0.4 (p < 0.05). The correlation value between the Borg and the OMNI RPE scales was r = 0.82 (p < 0.001). It can be concluded that indoor cycling elicits effort of high intensity which could be inappropriate for some participants. The Borg and OMNI scales showed a low validity to quantify the intensity performed in indoor cycling sessions. It indicates the necessity to control the intensity of effort with other instruments to improve efficacy and decrease the risk of overload in this activity.