IN-GAME HEART RATE RESPONSES AMONG PROFESSIONAL BASEBALL STARTING PITCHERS

The purpose of the current study was to characterize the in-game heart rate (HR) responses of baseball pitching. In-game HR was recorded from 16 professional baseball starting pitchers (mean +/- SD, age = 22.1 +/- 1.3 years; height = 187.9 +/- 4.4 cm; weight = 90.5 +/- 9.5 kg) for a total of 682 innings (home = 381, away = 301). All analyzed HR data were then normalized to each pitcher's age-predicted maximal HR (% HRmax). The group mean +/- SD in-game % HRmax among all pitchers was 84.8 +/- 3.9%, suggesting that baseball pitching is predominantly an anaerobic task. A split-plot mixed-model repeated measures analysis of variance identified a significant interaction effect between inning and game location (p = 0.042). Follow-up simple effects indicated that the in-game % HRmax was significantly different across innings, but only during home starts (p< 0.001). Specifically, pairwise analyses indicated that the in-game % HRmax during home starts were significantly (p <= 0.05) higher in the first and second innings than in all other innings. In addition, follow-up simple effects indicated that the in-game % HRmax was significantly (p = 0.017) higher during home starts than away starts in the first inning (87.3 +/- 3.% vs. 85.8 vs. 3.8%, respectively). Thus, it is possible that inning-dependent psychological factors may have contributed to the observed changes in in-game physiological intensity across innings and that these factors are specific to game location. Consequently, strength and conditioning practitioners should prescribe high-intensity exercises when developing conditioning programs for professional baseball starting pitchers.