Ratings of Perceived Exertion Throughout an Ultramarathon during Carbohydrate Ingestion

Analyzing Competitive Demands in Mountain Running Races: A Running Power-Based Approach

PURPOSE

This study aimed to analyze the competitive demands of mountain running races of varying lengths.

METHODS

Sixty-six male athletes competed in Vertical race (∼3 km and ∼1000 m of total elevation change), Sky race (∼25 km and ∼3000 m of total elevation change), and SkyUltra race (∼80 km and ∼9000 m of total elevation change). Exercise intensity and competition load (TL) were assessed using running power, heart rate, and rating of perceived exertion (RPE).

RESULTS

The highest exercise intensity was observed in Vertical race (3.9 [0.4] W·kg-1, 93.6% [2.8%] HRmax, and 9.5 [0.7] RPE) compared to Sky race (3.5 [0.5] W·kg-1, 89.9% [2.4%] HRmax, and 8.5 [1.2] RPE), and SkyUltra (2.7 [0.6] W·kg-1, 73.4% [1.1%] HRmax, and 8.2 [1.1] RPE). Vertical races had the highest mean maximal power outputs for periods <10 minutes. They also had the highest proportion of time spent >5 W·kg-1 and the most time spent above the respiratory compensation threshold. The majority of time in SkyUltra was spent at low intensity. The highest TLs were observed in these races (6200.5 [708.0] kJ, 842.0 [35.7] AU for TLHR, and 4897.3 [940.7] AU for TLRPE). However, when normalized to competition time, the SkyUltra event showed the lowest values compared with the Vertical and Sky races (∼11 vs ∼14.5 kJ·min-1, ∼1.5 vs ∼2.5 AU·m-1 for TLHR).

CONCLUSION

The results of this study expand knowledge about the effort demands of mountain races and demonstrate how these demands are affected by race duration. Additionally, the study highlights the potential use of running power for quantifying exercise in this sport.

Emotional intelligence and mood states impact on the stress response to a treadmill ultramarathon

OBJECTIVES

Participants of ultramarathon events experience a complex interaction of psychophysiological stressors. Therefore, the purpose of this study was to investigate the role of trait emotional intelligence (trait EI) on mood states and serum cortisol responses to a 80.5km treadmill ultramarathon.

DESIGN

Twelve participants completed an 80.5km time-trial on a motorised treadmill in the fastest possible time.

METHODS

Participants' trait EI was measured prior to the trial. A mood state questionnaire was completed prior (baseline: within two weeks of treadmill ultramarathon), immediately prior (pre: within 30min of commencing treadmill ultramarathon), at 40.25km (halfway: during standardised 10min rest period to allow for venous blood sampling) and on completion of 80.5km (post: immediately on completion of treadmill ultramarathon), along with serum cortisol concentrations measured at the same time points.

RESULTS

Completion time was 09:00:18±01:14:07 (hhmmss). Significant increase in serum cortisol and total mood disturbance (TMD) was observed throughout the treadmill ultramarathon (p<0.05). Participants with higher trait EI displayed a higher post cortisol concentration (p=0.01) with no change in TMD, compared to those with low trait EI who displayed a significant increase in TMD between pre and halfway (p=0.02).

CONCLUSIONS

The treadmill ultramarathon elicited a significant increase in serum cortisol concentration, which was significantly greater in those with a higher trait EI. Those individuals with higher trait EI were more effective at managing their mood, with little change total mood disturbance and perceived effort compared to those with lower trait EI.

Optimal pacing and carbohydrate intake strategies for ultramarathons

PURPOSE

The purpose of this research is to determine the pacing and nutrition strategies which minimize completion time and carbohydrate intake for athletes competing in ultramarathon races.

METHODS

We present the formulation of a two-phase optimization model. The first-phase mixed-integer nonlinear program (MINLP) determines the minimum completion time subject to the altitude, terrain, and distance of the race, as well as the mass and cardiovascular fitness of the athlete. The second-phase MINLP determines the minimum carbohydrate intake required for the athlete to achieve the completion time prescribed by the first-phase subject to the flow of carbohydrates through the stomach, liver, and muscles. Consequently, the second-phase model provides the optimal pacing and nutrition strategies for a particular athlete for each kilometer of a particular race.

RESULTS

We validate model results for a wide range of athlete parameters by comparing completion times to those reported for two case-study events. We also compare the kilometer-by-kilometer pacing and nutrition strategies prescribed by the model to those of a particular athlete. In all cases, the model results closely match those witnessed in the actual events.

CONCLUSION

We have developed a baseline metabolic model that provides athletes prescriptive guidance regarding optimal pacing and carbohydrate intake strategies prior to competing in ultramarathon races. Given the highly variable topographical characteristics common to many ultramarathon courses and the potential inexperience of many athletes with such courses, our model provides valuable insight to competitors who might otherwise fail to complete the event due to exhaustion or carbohydrate depletion.

The Dynamics of Speed Selection and Psycho-Physiological Load during a Mountain Ultramarathon

BACKGROUND

Exercise intensity during ultramarathons (UM) is expected to be regulated as a result of the development of psycho-physiological strain and in anticipation of perceived difficulties (duration, topography). The aim of this study was to investigate the dynamics of speed, heart rate and perceived exertion during a long trail UM in a mountainous setting.

METHODS

Fifteen participants were recruited from competitors in a 106 km trail mountain UM with a total elevation gain and loss of 5870 m. Speed and gradient, heart rate (HR) and ratings of perceived exertion (dissociated between the general [RPEGEN] and knee extensor fatigue [RPEKE] and collected using a voice recorder) were measured during the UM. Self-selected speed at three gradients (level, negative, positive), HR, RPEGEN and RPEKE were determined for each 10% section of total event duration (TED).

RESULTS

The participants completed the event in 18.3 ± 3.0 h, for a total calculated distance of 105.6 ± 1.8 km. Speed at all gradients decreased, and HR at all gradients significantly decreased from 10% to 70%, 80% and 90%, but not 100% of TED. RPEGEN and RPEKE increased throughout the event. Speed increased from 90% to 100% of TED at all gradients. Average speed was significantly correlated with total time stopped (r = -.772; p = .001; 95% confidence interval [CI] = -1.15, -0.39) and the magnitude of speed loss (r = .540; p = .038; 95% CI = -1.04, -0.03), but not with the variability of speed (r = -.475; p = .073; 95% CI = -1.00, 0.05).

CONCLUSIONS

Participants in a mountain UM event combined positive pacing strategies (speed decreased until 70-90% of TED), an increased speed in the last 10% of the event, a decrease in HR at 70-90% of TED, and an increase in RPEGEN and RPEKE in the last 30% of the event. A greater speed loss and less total time stopped were the factors associated with increased total performance. These results could be explained by theoretical perspectives of a complex regulatory system modulating motor drive in anticipation of perceived difficulties such as elevation changes.

Analysis of weight change and Borg rating of perceived exertion as measurements of runner health and safety during a 6-day, multistage, remote ultramarathon

OBJECTIVE

To determine the feasibility of using weight change and Borg score as tools for monitoring runner health and safety during a multistage, remote ultramarathon.

DESIGN

Observational cohort study of feasibility on nonblinded event participants.

SETTING

Six-day, multistage, remote ultramarathon in Utah.

PARTICIPANTS

Twenty-seven athletes in the 2012 Desert R.A.T.S. (Race Across the Sand) ultramarathon.

ASSESSMENT OF RISK FACTORS

Participant weight, health conditions that limited race participation, such as fatigue or exhaustion, and Borg score were reviewed.

MAIN OUTCOME MEASURES

Inability to complete a stage of the race (Did Not Finish status) or development of a clinically significant health condition during the race. Potential prognostic risk factors, such as a high Borg score and weight loss, were analyzed.

RESULTS

An overall decrease in weight was observed over the course of the event. Median percent weight changes were losses of 2.96% (day 1), 7.42% (day 2), 2.21% (day 4), and 3.35% (day 6). There was no statistically significant difference in percent weight change between the 14 runners who finished the race and the 13 runners who did not finish the race (U = 73; z = 0.189; P = 0.85). Runners' ability to complete the race was related to the development of adverse health conditions (P = 0.004). Median Borg scores reported were 15 (day 1), 17 (day 2), 13 (day 3), 16 (day 4), and 15 (day 6). Only 2 racers who finished the entire event without adverse events ever gave a Borg score of ≥ 18.

CONCLUSIONS

The feasibility of weight change as a tool for monitoring runner health and safety in this setting is limited, but the Borg rating of perceived exertion warrants further study as a potential field expedient tool for monitoring runner health and safety during a multiday, remote ultramarathon.

The differential effects of a complex protein drink versus isocaloric carbohydrate drink on performance indices following high-intensity resistance training: a two arm crossover design

Background

Post-workout nutrient timing and macronutrient selection are essential for recovery, glycogen replenishment and muscle protein synthesis (MPS). Performance repeatability, particularly after strenuous activity, can be influenced by substrate availability, recovery markers and perceived rate of exertion. This study compared the differential effects of a complex protein ready-to-drink beverage (VPX) and isocaloric carbohydrate beverage (iCHO) on performance—agility T-test, push-up test, 40-yard sprint, and rate of perceived exertion (RPE), following high-intensity resistance training (HIRT).

Methods

In a randomized, double blind two-arm crossover controlled trial, 15 subjects performed a 15–18 minute (2:1 work to rest) HIRT and then immediately drank one of the two treatments. After a 2-hour fast, subjects returned to execute the field tests and report RPE. The protocol was repeated one week later with the other treatment.

Results

There were no significant main effect differences in the agility T-test (p = 0.83), push-up (p = 0.21) sprint (p = 0.12), average agility RPE (p = 0.83), average push-up RPE (p = 0.81) or average sprint RPE (p = 0.66) between the two trials and the two treatments. The multivariate analysis yielded a cumulative significant interaction effect amongst the three performance variables after consuming VPX (p < 0.01). These results suggest a complex protein beverage is a better post-workout choice compared to an isocaloric carbohydrate beverage for repeated performance for activities that require multiple energy demands and athletic skills; however, this outcome was not observed for each single performance event or RPE.

Conclusion

When considering the collective physical effects of the agility T-test, push-up and sprint tests, a complex protein beverage may provide a recovery advantage as it relates to repeated-bout performance compared to an iCHO-only beverage. Additional research examining the chronic effects of post-exercise protein versus iCHO beverages on performance repeatability, particularly in special populations (e.g. tactical and elite athletes), is warranted to further develop these findings.

Scalar-linear increases in perceived exertion are dissociated from residual physiological responses during sprint-distance triathlon

OBJECTIVE

This study examined how residual fatigue affects the relationship between ratings of perceived exertion (RPE), physiological responses, and pacing during triathlon performance.

METHODS

Eight male triathletes completed a sprint-distance triathlon (750m swim, 20kmcycle and 5km run) and isolated 5km run on separate days. RPE, core temperature (Tcore), heart rate and blood lactate concentration [BLa(-)] were recorded during both, in addition to performance time and speed.

RESULTS

Triathlon run time (1248±121s) was significantly slower than the isolated run (1167±90s) (p<0.01). Significant differences were observed at the start of the two conditions for all physiological measures (Heart rate 162±4 vs 154±5 beatsmin(-1); Tcore 38.3±0.8 vs 36.7±0.6C; [BLa(-)] 9.1±2.8 vs 2.1±0.4mmolL(-1), for triathlon and isolated run, respectively, p<0.05). No significant differences were observed for initial RPE (p=0.083), rate of RPE increase (p=0.412), or final RPE (p=0.329) between run trials.

CONCLUSIONS

The maintenance of a scalar-linear increase in RPE by the brain remains the primary mechanism for pace regulation during both single and multi-modal endurance performance, with physiological responses being only indirectly related to this process. The apparent absence of any RPE 'resetting' between disciplines suggests that during shorter distance multi-sport performances (60-90 min) a cognitive pacing strategy for the entire event is employed. However, as subtle alterations in RPE development between disciplines were observed the existence of discipline-specific RPE 'templates' should not be discounted.

Can neuromuscular fatigue explain running strategies and performance in ultra-marathons?: the flush model

While the industrialized world adopts a largely sedentary lifestyle, ultra-marathon running races have become increasingly popular in the last few years in many countries. The ability to run long distances is also considered to have played a role in human evolution. This makes the issue of ultra-long distance physiology important. In the ability to run multiples of 10 km (up to 1000 km in one stage), fatigue resistance is critical. Fatigue is generally defined as strength loss (i.e. a decrease in maximal voluntary contraction [MVC]), which is known to be dependent on the type of exercise. Critical task variables include the intensity and duration of the activity, both of which are very specific to ultra-endurance sports. They also include the muscle groups involved and the type of muscle contraction, two variables that depend on the sport under consideration. The first part of this article focuses on the central and peripheral causes of the alterations to neuromuscular function that occur in ultra-marathon running. Neuromuscular function evaluation requires measurements of MVCs and maximal electrical/magnetic stimulations; these provide an insight into the factors in the CNS and the muscles implicated in fatigue. However, such measurements do not necessarily predict how muscle function may influence ultra-endurance running and whether this has an effect on speed regulation during a real competition (i.e. when pacing strategies are involved). In other words, the nature of the relationship between fatigue as measured using maximal contractions/stimulation and submaximal performance limitation/regulation is questionable. To investigate this issue, we are suggesting a holistic model in the second part of this article. This model can be applied to all endurance activities, but is specifically adapted to ultra-endurance running: the flush model. This model has the following four components: (i) the ball-cock (or buoy), which can be compared with the rate of perceived exertion, and can increase or decrease based on (ii) the filling rate and (iii) the water evacuated through the waste pipe, and (iv) a security reserve that allows the subject to prevent physiological damage. We are suggesting that central regulation is not only based on afferent signals arising from the muscles and peripheral organs, but is also dependent on peripheral fatigue and spinal/supraspinal inhibition (or disfacilitation) since these alterations imply a higher central drive for a given power output. This holistic model also explains how environmental conditions, sleep deprivation/mental fatigue, pain-killers or psychostimulants, cognitive or nutritional strategies may affect ultra-running performance.

Carbohydrate Attenuates Perceived Exertion during Intermittent Exercise and Recovery

PURPOSE

The purpose of this study was to examine the effect of carbohydrate supplementation on differentiated and undifferentiated ratings of perceived exertion (RPE) during prolonged intermittent exercise and recovery.

METHODS

Twelve male subjects cycled for 2.0 h at 64% Wmax and 73% V O2peak with 3-min rest intervals interspersed every 10 min (2.6 h of total exercise time, including rest intervals) with placebo (P) or carbohydrate (C) beverages. RPE was assessed during the last minute of each 10-min exercise interval and then every 30 s during the 3-min recovery period.

RESULTS

The pattern of change in RPE over time was significantly different between C and P ingestion (P < 0.05), with attenuated RPE responses found for both overall body (O) and legs (L). A significant main effect was found for recovery RPE-O between C and P ingestion (P < 0.05), with attenuated RPE responses found in the later part of the 2-h run. C relative to P ingestion was associated with higher respiratory exchange ratios and plasma levels of glucose and with lower levels of plasma cortisol.

CONCLUSIONS

These data indicate that carbohydrate supplementation attenuates perceived exertion during prolonged intermittent exercise and recovery.