Ballistic protective helmets can impair heat dissipation. A cooling device in the helmet (cooling pad, CP) could help prevent heat problems in military personnel and potentially enhance comfort. This study examined the effects of CP on rectal and skin temperatures, heart rate, percent change in plasma volume, urine specific gravity, rating of perceived exertion, and other subjective measures while performing light work in a hot environment. It was hypothesized that the CP would act as an insulator to the head, which would not positively affect any physiological variable but could positively affect wearer subjective comfort or temperature. Participants performed a work protocol for ∼ 2 hr. A ballistic vest, slacks, short-sleeved button-up shirt, and a ballistic helmet (one trial with CP and one trial without) were worn. Repeated measures analysis of variance (ANOVA) showed no differences (p > 0.05) between wearing and not wearing the CP for any physiological parameter. However, participants perceived the CP as cooler (p = 0.002). Other trends in perceptual data such as thermal strain and helmet comfort indicated the CP felt cooler. However, based on forehead temperature and participant comments, the CP lost its cooling ability relatively quickly (within ∼ 30 min).

Objective. To compare resistance bouts performed to failure atlow (60% 1RM) and high (90% 1RM) workloads for acute rate of perceived exertion (RPE) (per exercise), session RPE (S-RPE) (30 min post), HR (per exercise) and total work (per session, and per exercise).Background. RPE is a convenient method for quantifying intensityin aerobic exercise. However, RPE has recently been extended to exercise modalities dominated by anaerobic pathways such as resistance training (RT). Method. Subjects (N=12) were assessed using an exercise-specific1 repetition maximum (1RM) for 6 exercises. On separate days in a counterbalanced order, subjects performed 3 sets of each exercise to volitional failure at a low intensity (LI) and a high intensity (HI) with 2 minutes rest between sets and exercises. At the end of each set, subjects estimated acute RPE for that set using a 10-point numerical scale. Thirty minutes after the end of the exercise session subjects estimated their S-RPE for the entire workout. HR, total work, and acute RPE were compared (HI v. LI) using repeated measures ANOVA.Results. A paired samples t-test showed LI was significantly higher(p=0.039) than HI for session RPE (LI=8.8±0.8, HI=6.3±1.2) andtotal work (LI=17461±4419, HI=8659±2256) (p=0.043). Per exercise,total work and acute RPE were significantly greater (p=0.01) for LI for all exercises. Peak HR was significantly higher per exercise during LI for leg press (p=0.041), bench press (p=0.031), lat pull-down (p=0.037) and shoulder press (p=0.046).

AIM The potential influence of a hotter vs cooler environment on ratings of perceived exertion (RPE) estimations during longer duration exercise is not well-understood. This study compared overall and differentiated RPEs during cycling in 18 degrees C vs 30 degrees C wet bulb globe temperature (WBGT). METHODS Male volunteers (n=16) completed a maximal cycling trial (60 rev . min(-1), 25 Watts . min(-1)) to determine VO(2) max and ventilatory threshold (VT) before completing 2 (counterbalanced) longer duration cycling trials. At 30 degrees C WBGT (30C) and 18 degrees C WBGT (18C), subjects cycled 60 min (60 rev . min(-1), 90% individualized VT). Heart rate (HR, b . min(-1)) and rectal temperature (Tre, degrees C) were recorded every 5 min with corresponding RPE-overall (RPE-O), RPE-legs (RPE-L) and RPE-chest (RPE-C) estimations. RESULTS HR was not significantly different at 5 min but was greater (P<0.05) for 30C at all other time points. During 30C, Tre was significantly greater (25, 30, 35, 40, 45, 50, 55 and 60 min), RPE-O was significantly greater (5, 40, 45, 50, 55 and 60 min), RPE-L was significantly greater (55 and 60 min) and RPE-C was significantly greater (35, 40, 45, 50, 55 and 60 min). CONCLUSIONS Greater cardiovascular (HR) and thermal (Tre) strain partially explain greater perceptual ratings during 30C. Discernible RPE differences resulted mid-way through 60 min cycling with minimal differences initially. Results suggest RPEs are magnified in a 30 degrees C (vs 18 degrees C) environment beyond 30 min duration. Additionally, a 30 degrees C environment resulted in a less pronounced impact on RPE-L (vs RPE-C and RPE-O).

PURPOSE:Physiological and perceptual measures during interval exercise are not well understood. The current study therefore examined the correspondence between RPE, HR, and blood lactate concentration ([La]) during interval cycling. METHODS:VO2peak and the 4.0 mmol x L(-1) lactate threshold were determined. In session 2, subjects (N = 12) warmed up (10 min, 0 W) and completed five 2-min intervals (INT) at >4 mmol x L(-1) workload, each separated by 3 min of recovery (REC) (60 rpm, 0 W). HR, RPE, and [La] were recorded at 10 min, at the conclusion of each INT, and each REC and 5- and 10-min recovery. RESULTS:Repeated-measures ANOVA showed [La], HR, and RPE increased significantly across time (INT and REC). At each time point, repeated-measures ANOVA was used to compare standardized data (alpha = 0.05). RPE (at INT) intensified concurrently with HR and [La] at INT. Correlations were significant for INT (P < or = 0.05) (HR-RPE: r = 0.63, [La]-RPE: r = 0.43). Similarly, RPE and HR for REC systematically increased with [La]. Correlations for REC were also significant (HR-RPE: r = 0.44, [La]-RPE: r = 0.34). Correlations were also significant for INT and REC combined (HR-RPE: r = 0.70, [La]-RPE: r = 0.22). CONCLUSIONS:INT and REC independently showed moderate correspondence for RPE-[La] and RPE-HR. However, tighter overall coupling of HR with RPE (vs [La] with RPE) and a dissociation between RPE-[La] suggest RPE during intervals of intense cycling were more sensitive to acute metabolic demand (evidenced by HR) versus [La].

This study examined the association of blood lactate concentration [La] and heart rate (HR) with ratings of perceived exertion (RPE) during 60 min of steady workload cycling. Physically active college-aged subjects (n = 14) completed an exhaustive cycling test to determine VO(2) (peak) and lactate threshold (2.5 mmol l(-1)). Subjects then cycled for 60 min at the power output associated with 2.5 mmol l(-1) [LA]. HR, [LA], RPE-overall, RPE-legs and RPE-chest were recorded at 5, 10, 20, 30, 40, 50 and 60 min. The 60-min trials were below maximal lactate steady state, with peak lactate concentration occurring at 20 min after which [LA] declined. The 20-min point was therefore considered pivotal, and data at other points were compared to this time point. Repeated measures ANOVA with simple contrasts (alpha = 0.05) showed (a) [LA] at 40, 50 and 60 min was significantly lower than at 20 min, (b) RPE-O and RPE-L were significantly greater at 30, 40, 50 and 60 min than at 20 min, (c) RPE-C was significantly greater at 40, 50 and 60 min than at 20 min, and (d) HR was significantly greater at 30, 40, 50 and 60 min than at 20 min. Significant (P < 0.05) positive correlations were found between HR and RPE-O (r = 0.43), RPE-L (r = 0.48) and RPE-C (r = 0.41) while correlations for [LA]-HR (r = 0.13) and [LA]-RPE (RPE-O: r = -0.11, RPE-L: r = 0.01, RPE-C: r = -0.06) were weak and non-significant. There is a dissociation of RPE and [LA] owing to RPE drift and lactate kinetics in longer duration sub-maximal exercise. Apparently, [LA] is not a strong RPE mediator during extended cycling.