Use of CR100 Scale for Session Rating of Perceived Exertion in Soccer and Its Interchangeability With the CR10.

PURPOSE: To examine the construct validity of the session rating perceived exertion (s-RPE) assessed with the Borg CR100 scale to measure training loads in elite soccer and to examine if the CR100 is interchangeable and can provide more-accurate ratings than the CR10 scale. METHODS: Two studies were conducted. The validity of the CR100 was determined in 19 elite soccer players (age 28 ± 6 y, height 180 ± 7 cm, body mass 77 ± 6 kg) during training sessions through correlations with the Edwards heart-rate method (study 1). The interchangeability with CR10 was assessed in 78 soccer players (age 19.3 ± 4.1 y, height 178 ± 5.9 cm, body mass 71.4 ± 6.1 kg) through the Bland-Altman method and correlations between change scores in different sessions. To examine whether the CR100 is more finely graded than the CR10, the proportions of responses corresponding to the verbal expressions were calculated (study 2). RESULTS: Individual correlations between the Edwards method and s-RPE were large to very large (.52-.85). The mean difference between the 2 scales was -0.3 ± 0.33 AU (90% CI -0.41 to -0.29) with 95% limits of agreements (0.31 to -0.96 AU). Correlations between scales and between-changes scores were nearly perfect (.95 and .91-.98). Ratings corresponding to the verbal anchors were 49% in CR10 and 26% in CR100. CONCLUSIONS: The CR100 is valid for assessing the training load in elite soccer players. It can be used interchangeably with the CR10 and may provide more-precise measures of exercise intensity.

Match-related fatigue in soccer players.

UNLABELLED: Soccer induces neuromuscular fatigue requiring several hours of recovery. PURPOSE: The study aimed to determine the extent to which neuromuscular fatigue occurs in high-level professional players and its recovery after a match and to examine its relationship with central and peripheral fatigue indicators. METHODS: Maximal voluntary contraction (MVC), sprint and passing abilities, muscle soreness, maximal voluntary activation, EMG activity, and evocated quadriceps contractile properties (using different electrical stimulations) were determined before, immediately after, and at 24 and 48 h after the match in 20 male professional players. RESULTS: Immediately after a 90-min game, fatigue was evident by a reduction of MVC and sprint performance (-11%, P < 0.001 and -3%, P < 0.001, respectively) and increased muscle soreness (P < 0.001) compared with baseline, whereas short-passing ability was preserved. At the same time point, maximal voluntary activation and EMG activity were reduced by 8% (P < 0.001) and 12% (P = 0.001), respectively. M-wave characteristics were unchanged, whereas quadriceps mechanical responses to single and paired stimulations at 10 Hz resulted as significantly reduced (peak torque = -8%, P < 0.001 and -9%, P < 0.001). Despite the observation of a partial recovery 24 h after the game, all variables did not return to baseline values until 48 h after the match. CONCLUSIONS: In high-level professional players, the fatigue induced by a soccer match occurs to a smaller extent than in lower level athletes and seems to be recovered in a faster fashion. Match-related fatigue is determined by a combination of central and peripheral factors. A relationship exists between central fatigue indicators and MVC and sprint performance decrements, whereas muscle soreness seems to be linked to peripheral fatigue indicators, particularly to mechanical responses at low-frequency stimulations.