Exercise Dose Equalization in High-Intensity Interval Training: A Scoping Review

Based on comparisons to moderate continuous exercise (MICT), high-intensity interval training (HIIT) is becoming a worldwide trend in physical exercise. This raises methodological questions related to equalization of exercise dose when comparing protocols. The present scoping review aims to identify in the literature the evidence for protocol equalization and the soundness of methods used for it. PubMed and Scopus databases were searched for original investigations comparing the effects of HIIT to MICT. A total of 2041 articles were identified, and 169 were included. Of these, 98 articles equalized protocols by utilizing energy-based methods or exercise volume (58 and 31 articles, respectively). No clear consensus for protocol equalization appears to have evolved over recent years. Prominent equalization methods consider the exercise dose (i.e., energy expenditure/production or total volume) in absolute values without considering the nonlinear nature of its relationship with duration. Exercises resulting from these methods induced maximal exertion in HIIT but low exertion in MICT. A key question is, therefore, whether exercise doses are best considered in absolute terms or relative to individual exercise maximums. If protocol equalization is accepted as an essential methodological prerequisite, it is hypothesized that comparison of program effects would be more accurate if exercise was quantified relative to intensity-related maximums

The effects of intensified training on resting metabolic rate (RMR), body composition and performance in trained cyclists

<div><p>Background</p><p>Recent research has demonstrated decreases in resting metabolic rate (RMR), body composition and performance following a period of intensified training in elite athletes, however the underlying mechanisms of change remain unclear. Therefore, the aim of the present study was to investigate how an intensified training period, designed to elicit overreaching, affects RMR, body composition, and performance in trained endurance athletes, and to elucidate underlying mechanisms.</p><p>Method</p><p>Thirteen (n = 13) trained male cyclists completed a six-week training program consisting of a “Baseline” week (100% of regular training load), a “Build” week (~120% of Baseline load), two “Loading” weeks (~140, 150% of Baseline load, respectively) and two “Recovery” weeks (~80% of Baseline load). Training comprised of a combination of laboratory based interval sessions and on-road cycling. RMR, body composition, energy intake, appetite, heart rate variability (HRV), cycling performance, biochemical markers and mood responses were assessed at multiple time points throughout the six-week period. Data were analysed using a linear mixed modeling approach.</p><p>Results</p><p>The intensified training period elicited significant decreases in RMR (F_(5,123.36) = 12.0947, p = <0.001), body mass (F_(2,19.242) = 4.3362, p = 0.03), fat mass (F_(2,20.35) = 56.2494, p = <0.001) and HRV (F_(2,22.608) = 6.5212, p = 0.005); all of which improved following a period of recovery. A state of overreaching was induced, as identified by a reduction in anaerobic performance (F_(5,121.87) = 8.2622, p = <0.001), aerobic performance (F_(5,118.26) = 2.766, p = 0.02) and increase in total mood disturbance (F_{(5, 110.61)} = 8.1159, p = <0.001).</p><p>Conclusion</p><p>Intensified training periods elicit greater energy demands in trained cyclists, which, if not sufficiently compensated with increased dietary intake, appears to provoke a cascade of metabolic, hormonal and neural responses in an attempt to restore homeostasis and conserve energy. The proactive monitoring of energy intake, power output, mood state, body mass and HRV during intensified training periods may alleviate fatigue and attenuate the observed decrease in RMR, providing more optimal conditions for a positive training adaptation.</p></div

New approaches to determine fatigue in elite athletes during intensified training:Resting metabolic rate and pacing profile

BACKGROUND:Elite rowers complete a high volume of training across a number of modalities to prepare for competition, including periods of intensified load, which may lead to fatigue and short-term performance decrements. As yet, the influence of substantial fatigue on resting metabolic rate (RMR) and exercise regulation (pacing), and their subsequent utility as monitoring parameters, has not been explicitly investigated in elite endurance athletes. METHOD:Ten National-level rowers completed a four-week period of intensified training. RMR, body composition and energy intake were assessed PRE and POST the four-week period using indirect calorimetry, Dual-Energy X-Ray Densitometry (DXA), and three-day food diary, respectively. On-water rowing performance and pacing strategy was evaluated from 5 km time trials. Wellness was assessed weekly using the Multicomponent Training Distress Scale (MTDS). RESULTS:Significant decreases in absolute (mean ± SD of difference, p-value: -466 ± 488 kJ.day-1, p = 0.01) and relative RMR (-8.0 ± 8.1 kJ.kg.FFM-1, p = 0.01) were observed. Significant reductions in body mass (-1.6 ± 1.3 kg, p = 0.003) and fat mass (-2.2 ± 1.2 kg, p = 0.0001) were detected, while energy intake was unchanged. On-water 5 km rowing performance worsened (p < 0.05) and an altered pacing strategy was evident. Fatigue and total mood disturbance significantly increased across the cycle (p < 0.05), and trends were observed for reduced vigour and increased sleep disturbance (p < 0.1). CONCLUSION:Four weeks of heavy training decreased RMR and body composition variables in elite rowers and induced substantial fatigue, likely related to an imbalance between energy intake and output. This study demonstrates that highly experienced athletes do not necessarily select the correct energy intake during periods of intensified training, and this can be assessed by reductions in RMR and body composition. The shortfall in energy availability likely affected recovery from training and altered 5 km time trial pacing strategy, resulting in reduced performance

Trends in triathlon performance: Effects of sex and age

The influences of sex and age upon endurance performance have previously been documented for both running and swimming. A number of recent studies have investigated how sex and age influence triathlon performance, a sport that combines three disciplines (swimming, cycling and running), with competitions commonly lasting between 2 (short distance: 1.5-km swim, 40-km cycle and 10-km run) and 8 h (Ironman distance: 3.8-km swim, 180-km cycle and 42-km run) for elite triathletes. Age and sex influences upon performance have also been investigated for ultra-triathlons, with distances corresponding to several Ironman distances and lasting several days, and for off-road triathlons combining swimming, mountain biking and trail running. Triathlon represents an intriguing alternative model for analysing the effects of age and sex upon endurance and ultra-endurance (>6 h) performance because sex differences and age-related declines in performance can be analysed in the same individuals across the three separate disciplines. The relative participation of both females and masters athletes (age >40 years) in triathlon has increased consistently over the past 25 years. Sex differences in triathlon performance are also known to differ between the modes of locomotion adopted (swimming, cycling or running) for both elite and non-elite triathletes. Generally, time differences between sexes in swimming have been shown to be smaller on average than during cycling and running. Both physiological and morphological factors contribute to explaining these findings. Performance density (i.e. the time difference between the winner and tenth-placed competitor) has progressively improved (time differences have decreased) for international races over the past two decades for both males and females, with performance density now very similar for both sexes. For age-group triathletes, sex differences in total triathlon performance time increases with age. However, the possible difference in age-related changes in the physiological determinants of endurance and ultra-endurance performances between males and females needs further investigation. Non-physiological factors such as low rates of participation of older female triathletes may also contribute to the greater age-related decline in triathlon performance shown by females. Total triathlon performance has been shown to decrease in a curvilinear manner with advancing age. However, when triathlon performance is broken down into its three disciplines, there is a smaller age-related decline in cycling performance than in running and swimming performances. Age-associated changes in triathlon performance are also related to the total duration of triathlon races. The magnitude of the declines in cycling and running performances with advancing age for short triathlons are less pronounced than for longer Ironman-distance races. Triathlon distance is also important when considering how age affects the rate of the decline in performance. Off-road triathlon performances display greater decrements with age than road-based triathlons, suggesting that the type of discipline (road vs. mountain bike cycling and road vs. trail running) is an important factor in age-associated changes in triathlon performance. Finally, masters triathletes have shown relative improvements in their performances across the three triathlon disciplines and total triathlon event times during Ironman races over the past three decades. This raises an important issue as to whether older male and female triathletes have yet reached their performance limits during Ironman triathlons

Genetic polymorphisms influence runners’ responses to the dietary ingestion of antioxidant supplementation based on pequi oil (Caryocar brasiliense Camb.): a before-after study

Genes have been implicated in the levels of oxidative stress, lipids, CVD risk, immune reactivity, and performance. Pequi oil (Caryocar brasiliense) has shown anti-inflammatory and hypotensive effects, besides reducing exercise-induced DNA, tissue damages, and anisocytosis. Given that diet can interact with the human genome to influence health and disease, and because genetic variability can influence response to diet, we aim to investigate the influence of 12 gene polymorphisms on inflammatory markers, postprandial lipids, arterial pressure, and plasma lipid peroxidation of runners (N = 125), before and after 14 days of 400 mg pequi-oil supplementation, after races under closely comparable conditions. Arterial pressure was checked before races; blood samples were taken immediately after racing to perform leukogram and plateletgram, Tbars assay, lipid, and CRP dosages and genotyping. CAT, GST-M1/T1, CRP-G1059C, and MTHFR-C677T polymorphisms influenced post-pequi-oil responses in leukogram; Hp and MTHFR-C677T, in plateletgram; Hp, ACE, GSTT1, and MTHFR-A1298C, in lipid profile; MTHFR-A1298C, in C-reactive protein (CRP) levels; and Hp and MnSOD, in Tbars assay. Differences between ACE genotypes in leukogram and total cholesterol disappeared after pequi, and the same occurred for Hp and MnSOD in Tbars assay and for MTHFR-A1298C with CRP levels. Because genetic inheritance is one of the factors that drive atherosclerosis-related lipid abnormalities, results can contribute to a greater understanding of the influence of genetic polymorphisms in situations that push up free radicals. Knowledge is also expanded on how antioxidant supplementation affects an individual’s genes and how athletic genetic makeup can affect the way a person responds to antioxidant supplements