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Individual (orange: HVYTRAD; blue: HVYTHR) responses in oxygen uptake expressed relative to maximum oxygen uptake (a, b), heart rate expressed relative to maximum heart rate (c, d), and blood lactate (e, f).
Source publication
The objective of this study was to determine whether the variability in exercise tolerance and physiological responses is lower when exercise is prescribed relative to physiological thresholds (THR) compared to traditional intensity anchors (TRAD). Ten individuals completed a series of maximal exercise tests and a series of moderate (MOD), heavy (H...
Citations
... Increases in blood lactate concentration ([BLa]) occur when the rate of muscle lactate production exceeds the rate of lactate clearance from blood and reflect the metabolic response induced by exercise (Broskey et al. 2020;Gorostiaga et al. 2014). Large interindividual variability exists in the observed [BLa] response induced by a range of exercise intensities (Bonafiglia et al. 2018;Bossi et al. 2023;Iannetta et al. 2020;McConell et al. 2020;Meyler et al. 2023;Scharhag-Rosenberger et al. 2010). However, the rigorous methodology required to isolate interindividual variability in exercise response from random error has yet to be implemented. ...
... Anchoring exercise intensity to V O 2 peak or WRpeak (traditional method of exercise prescription; TRAD) yields large variability in the [BLa] exercise response, possibly because of interindividual differences in LT%peak and CP%max. Threshold-based prescription (THR) anchors intensity to either LT and/ or CP and is speculated to standardize domain intensity, thereby reducing interindividual variability in exercise/ [BLa] response (Dalleck et al. 2016;Lansley et al. 2011;Meyler et al. 2023;Wolpern et al. 2015). However, previous observations of reduced interindividual variability following THR were also accompanied by reduced absolute exercise intensity compared to TRAD (Meyler et al. 2023). ...
... Threshold-based prescription (THR) anchors intensity to either LT and/ or CP and is speculated to standardize domain intensity, thereby reducing interindividual variability in exercise/ [BLa] response (Dalleck et al. 2016;Lansley et al. 2011;Meyler et al. 2023;Wolpern et al. 2015). However, previous observations of reduced interindividual variability following THR were also accompanied by reduced absolute exercise intensity compared to TRAD (Meyler et al. 2023). Thus, it is currently unclear if interindividual variability in [BLa] response is caused by interindividual differences in LT%peak and CP%peak. ...
Purpose
(1) To determine if the blood lactate concentration ([BLa]) response is a repeatable individual trait, and (2) To examine whether threshold-based prescription (THR) reduces interindividual variability in [BLa] response compared to traditional (maximally anchored) exercise prescription (TRAD).
Method
A crossover within-participant repeated measures design was used to assess [BLa] during the TRAD and THR exercise in 17 participants (9 M/8F). Participants initially undertook an incremental test to exhaustion to determine peak work rate (WRpeak), a lactate threshold (LT) test and a critical power (CP) test. All baseline tests were repeated twice. Participants then completed 6 15-min bouts of continuous cycling at 65%WRpeak (TRAD; 3 bouts) and 80% of the difference (Δ80) between LT and CP (THR; 3 bouts). [BLa] response was measured at 10 and 15 min of exercise.
Results
Across individuals, there was a wide range in [BLa] response, but within individual responses were repeatable. [BLa] ranges and mean individual 90% confidence interval width (CIw) were as follows: TRAD@10 min = 2.1–9.7 mmol, CIw = 0.5 mmol, THR@10 min = 3.4–9.3 mmol, CIw = 0.6 mmol, TRAD@15 min = 2.2–9.9 mmol, CIw = 0.6 mmol, THR@15 min = 3.6–12.3 mmol, CIw = 0.7 mmol. Levene’s tests revealed no significant differences in the variability of [BLa] response between TRAD and THR at 10 min (F = 0.523, p = 0.475) or 15 min (F = 0.351, p = 0.558) of exercise.
Conclusion
Our results demonstrate that true interindividual variability in the [BLa] response to exercise exists, but failed to confirm that variability in [BLa] response is reduced with the use of THR.
... have affected ECG-waveform morphology due to shifts in the cardiac axis (Aström et al., 2003). External load prescription assumes that physiological responses are rather static (Jamnick et al., 2020;Maunder et al., 2021) and neglect the influence of internal and external factors leading to heterogeneity in exercise tolerance and physiological responses over time (e.g., personal or environmental factors, Gronwald, Törpel, et al., 2020;Meyler et al., 2023). ...
Aim was to evaluate alterations of the non‐linear short‐term scaling exponent alpha1 of detrended fluctuation analysis (DFAa1) of heart rate (HR) variability (HRV) as a sensitive marker for assessing global physiological demands during multiple running intervals. As a secondary analysis, agreement of ECG‐derived respiratory frequency (EDR) compared to respiratory frequency (RF) derived from the metabolic cart was evaluated with the same chest belt device. Fifteen trained female and male long‐distance runners completed four running bouts over 5 min on a treadmill at marathon pace. During the last 3 min of each bout gas exchange data and a single‐channel ECG for the determination of HR, DFAa1 of HRV, EDR and RF were analyzed. Additionally, blood lactate concentration (BLC) was determined and rating of perceived exertion (RPE) was requested. DFAa1, oxygen consumption, BLC, and RPE showed stable behaviors comparing the running intervals. Only HR (p < 0.001, d = 0.17) and RF (p = 0.012, d = 0.20) indicated slight increases with small effect sizes. In addition, results point towards inter‐individual differences in all internal load metrics. The comparison of EDR with RF during running revealed high correlations (r = 0.80, p < 0.001, ICC3,1 = 0.87) and low mean differences (1.8 ± 4.4 breaths/min), but rather large limits of agreement with 10.4 to −6.8 breaths/min. Results show the necessity of EDR methodology improvement before being used in a wide range of individuals and sports applications. Relationship of DFAa1 to other internal load metrics, including RF, in quasi‐steady‐state conditions bears the potential for further evaluation of exercise prescription and may enlighten decoupling mechanisms during prolonged exercise bouts.
... The 95% PI for the difference between POL and PYR was SMD of − 0.06, 95% PI − 0.40 to 0.28 for V O 2peak , and SMD − 0.05, 95% PI − 0.40 to 0.30 for TT performance. This is consistent with previous observations that when training is prescribed by individualized intensity zones, the variability in responsiveness to the intervention is reduced [3,67,68]. PIs show the real variability in responses among the population of endurance-trained athletes to different TID models. While there were no detectable differences between TID models at the group level in this review, individual athletes may respond better or worse to a particular intervention within a wide range around the group mean. ...
Background
Endurance athletes tend to accumulate large training volumes, the majority of which are performed at a low intensity and a smaller portion at moderate and high intensity. However, different training intensity distributions (TID) are employed to maximize physiological and performance adaptations.
Objective
The objective of this study was to conduct a systematic review and network meta-analysis of individual participant data to compare the effect of different TID models on maximal oxygen uptake (VO2max) and time-trial (TT) performance in endurance-trained athletes.
Methods
Studies were included if: (1) they were published in peer reviewed academic journals, (2) they were in English, (3) they were experimental or quasi-experimental studies, (4) they included trained endurance athletes, (5) they compared a polarized (POL) TID intervention to a comparator group that utilized a different TID model, (6) the duration in each intensity domain could be quantified, and (7) they reported VO2max or TT performance. Medline and SPORTDiscus were searched from inception until 11 February 2024.
Results
We included 13 studies with 348 (n = 296 male, n = 52 female) recreational (n = 150) and competitive (n = 198) endurance athletes. Mean age ranged from 17.6 to 41.5 years and VO2max ranged from 46.6 to 68.3 mL·kg⁻¹·min⁻¹, across studies respectively. Based on the time in heart rate zone approach, there was no difference in VO2max (SMD = − 0.06, p = 0.68) or TT performance (SMD = − 0.05, p = 0.34) between POL and pyramidal (PYR) interventions. There were no statistically significant differences between POL and any of the other TID interventions. Subgroup analysis showed a statistically significant difference in the response of VO2max between recreational and competitive athletes for POL and PYR (SMD = − 0.63, p < 0.05). Competitive athletes may have greater improvements to VO2max with POL, while recreational athletes may improve more with a PYR TID.
Conclusions
Our results indicate that the adaptations to VO2max following different TID interventions are dependent on performance level. Athletes at a more competitive level may benefit from a POL TID intervention and recreational athletes from a PYR TID intervention.
... However, using physiological thresholds, and particularly using CP to prescribe high-intensity exercise, has been shown to reduce response variability, which results in a more consistent exercise session among individuals (Meyler et al., 2023). Repeated over time, exercise sessions where the intensity is prescribed relative to physiological thresholds appear to have an impact on the effectiveness of endurance training at improving fitness outcomes, such asV O 2 max . ...
... Meyler, S., Bottoms, L., Wellsted, D., Muniz-Pumares, D. (2023). Variability in exercise tolerance and physiological responses to exercise prescribed relative to physiological thresholds and to maximum oxygen uptake. ...
... Experimental Physiology. 2024;1-3. wileyonlinelibrary.com/journal/eph participants took part in a training programme where exercise intensity was anchored to a physiological threshold.Meyler et al. (2023) tested the consequences of this in the central paper of this connections article. They hypothesised that prescribing exercise relative to traditional anchors of exercise intensity, such as a percentage ofV O 2 max , would result in higher inter-individual variability in acute physiological responses to exercise, compared to when intensi ...
... Elevated BL levels and accompanying H + accumulation have long been associated with impaired musculoskeletal mitochondrial function and exercise tolerance [13,14], which are also directly related to the recovery process of the musculoskeletal system [15]. Tullberg et al. [16] reported that lower BL induced by PBMT could be caused by several factors, such as improved microcirculation and increased in blood flow. ...
... RPE was measured using the RPE scale (range, [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20], which ranges from 6 to 20, a common tool for gauging the perceived exertion level during physical activity [22]. This scale evaluates the subjective experience of effort, strain, or fatigue that participants feel while exercising. ...
The application of photobiomodulation therapy (PBMT) to delay skeletal muscle fatigue and shield against muscle damage represents a novel frontier in the field of exercise physiology. Further research is warranted to understand the physiological impact of PBMT on post-exercise recovery and muscle functionality. The objective of this research is to assess the impact of PBMT on the quadriceps following strenuous cycling, focusing on blood lactate (BL) levels, heart rate (HR), perceived exertion (RPE), and performance in the Wingate (WG) test. The study involved 12 male participants who were randomly allocated to either an active PBMT group or a control group, with treatments administered to the rectus femoris muscles bilaterally post-exhaustive cycling. The cycling exercise workload was 50 Watts (W); it increased by 50 W every 30 s at 60 rpm until the onset of exhaustion; and 30 s of active recovery was allowed between intervals. The BL, HR, and RPE were measured at several time points: pre-exercise, post-exercise, and at 10 min and 20 min post-exercise, as well as post-WG test. BL was significantly reduced in the PBMT group compared to the placebo group at the 10-min (p < 0.05) and 20-min (p < 0.01) marks post-exercise, and also post-WG test (p < 0.01). Additionally, HR was significantly lower in the PBMT group immediately following the WG test (p < 0.01). Both the mean (p < 0.05) and peak power outputs (p < 0.05) were found to be superior in the PBMT group. The application of PBMT to the quadriceps post-exhaustive exercise resulted in reduced BL and HR, along with improved WG test results, suggesting that PBMT may facilitate faster recovery following physical exertion.
... Exercise has benefits for many clinically important outcomes in older adults, such as reducing fall risk, cardiovascular disease, and death. However, despite engaging in exercise at the same relative intensity, not only young but also older populations exhibit significant variations in acute physiological responses to exercise and the time to task failure [601]. Understanding the threshold and optimal levels of activity necessary for health promotion and disease management has become increasingly important in recent years [602]. ...
Aging, a universal and inevitable process, is characterized by a progressive accumulation of physiological alterations and functional decline over time, leading to increased vulnerability to diseases and ultimately mortality as age advances. Lifestyle factors, notably physical activity (PA) and exercise, significantly modulate aging phenotypes. Physical activity and exercise can prevent or ameliorate lifestyle-related diseases, extend health span, enhance physical function, and reduce the burden of non-communicable chronic diseases including cardiometabolic disease, cancer, musculoskeletal and neurological conditions, and chronic respiratory diseases as well as premature mortality.
Physical activity influences the cellular and molecular drivers of biological aging, slowing aging rates—a foundational aspect of geroscience. Thus, PA serves both as preventive medicine and therapeutic agent in pathological states. Sub-optimal PA levels correlate with increased disease prevalence in aging populations. Structured exercise prescriptions should therefore be customized and monitored like any other medical treatment, considering the dose-response relationships and specific adaptations necessary for intended outcomes. Current guidelines recommend a multifaceted exercise regimen that includes aerobic, resistance, balance, and flexibility training through structured and incidental (integrated lifestyle) activities.
Tailored exercise programs have proven effective in helping older adults maintain their functional capacities, extending their health span, and enhancing their quality of life. Particularly important are anabolic exercises, such as Progressive resistance training (PRT), which are indispensable for maintaining or improving functional capacity in older adults, particularly those with frailty, sarcopenia or osteoporosis, or those hospitalized or in residential aged care. Multicomponent exercise interventions that include cognitive tasks significantly enhance the hallmarks of frailty (low body mass, strength, mobility, PA level, and energy) and cognitive function, thus preventing falls and optimizing functional capacity during aging. Importantly, PA/exercise displays dose-response characteristics and varies between individuals, necessitating personalized modalities tailored to specific medical conditions. Precision in exercise prescriptions remains a significant area of further research, given the global impact of aging and broad effects of PA.
Economic analyses underscore the cost benefits of exercise programs, justifying broader integration into health care for older adults. However, despite these benefits, exercise is far from fully integrated into medical practice for older people. Many healthcare professionals, including geriatricians, need more training to incorporate exercise directly into patient care, whether in settings including hospitals, outpatient clinics, or residential care. Education about the use of exercise as isolated or adjunctive treatment for geriatric syndromes and chronic diseases would do much to ease the problems of polypharmacy and widespread prescription of potentially inappropriate medications. This intersection of prescriptive practices and PA/exercise offers a promising approach to enhance the well-being of older adults. An integrated strategy that combines exercise prescriptions with pharmacotherapy would optimize the vitality and functional independence of older people whilst minimizing adverse drug reactions.
This consensus provides the rationale for the integration of PA into health promotion, disease prevention, and management strategies for older adults. Guidelines are included for specific modalities and dosages of exercise with proven efficacy in randomized controlled trials. Descriptions of the beneficial physiological changes, attenuation of aging phenotypes, and role of exercise in chronic disease and disability management in older adults are provided. The use of exercise in cardiometabolic disease, cancer, musculoskeletal conditions, frailty, sarcopenia, and neuropsychological health is emphasized. Recommendations to bridge existing knowledge and implementation gaps and fully integrate PA into the mainstream of geriatric care are provided. Particular attention is paid to the need for personalized medicine as it applies to exercise and geroscience, given the inter-individual variability in adaptation to exercise demonstrated in older adult cohorts. Overall, this consensus provides a foundation for applying and extending the current knowledge base of exercise as medicine for an aging population to optimize health span and quality of life.
... Similarly, two short-term continuous exercise training programs of different intensities (i.e., 50% and 70% of V O 2max ) elicited similar speeding of the V O 2 kinetics response (Murias et al. 2016). However, the intensity of the continuous training was prescribed as a percentage of V O 2max , a method that has been demonstrated to lack accuracy in ensuring uniform metabolic disturbance across individuals (Scharhag-Rosenberger et al. 2009;Iannetta et al. 2020;Meyler et al. 2023). Furthermore, the aforementioned exercise interventions were work-matched in only one of the studies (Berger et al. 2006), which does not allow for the isolation of the role of intensity. ...
Purpose
This study examined the effect of 3 and 6 weeks of intensity domain-based exercise training on kinetics changes and their relationship with indices of performance.
Methods
Eighty-four young healthy participants (42 M, 42 F) were randomly assigned to six groups (14 participants each, age and sex-matched) consisting of: continuous cycling in the (1) moderate (MOD)-, (2) lower heavy (HVY1)-, and (3) upper heavy-intensity (HVY2)- domain; interval cycling in the (4) severe-intensity domain (i.e., high-intensity interval training (HIIT), or (5) extreme-intensity domain (i.e., sprint-interval training (SIT)); or (6) control (CON). Training participants completed two three-week phases of three supervised sessions per week, with physiological evaluations performed at PRE, MID and POST intervention. All training protocols, except SIT, were work-matched.
Results
There was a significant time effect for the time constant () between PRE (31.6 ± 10.4 s) and MID (22.6 ± 6.9 s) (p < 0.05) and PRE and POST (21.8 ± 6.3 s) (p < 0.05), but no difference between MID and POST (p > 0.05) and no group or interaction effects (p > 0.05). There were no PRE to POST differences for CON (p < 0.05) in any variables. Despite significant increases in maximal (), estimated lactate threshold (θLT), maximal metabolic steady state (MMSS), and peak power output (PPO) for the intervention groups (p < 0.05), there were no significant correlations from PRE to MID or MID to POST between and (r = – 0.221, r = 0.119), ΔPPO (r = – 0.112, r = – 0.017), ΔθLT (r = 0.083, r = 0.142) and ΔMMSS (r = – 0.213, r = 0.049)(p > 0.05).
Conclusion
This study demonstrated that (i) the rapid speeding of kinetics was not intensity-dependent; and (ii) changes in indices of performance were not significantly correlated with .
... The three-zone TID model was initially proposed by Skinner and McLellan [5] on the basis of changes in gas exchange and blood lactate. More recently, three-zone TID models have been aligned with the moderate, heavy and severe exercise intensity domains, whereby each exercise domain elicits distinct and well-defined physiological responses to exercise [6][7][8]. Using a three-zone TID framework, zone 1 (Z1) comprises intensities up to the lactate threshold or gas exchange threshold, zone 2 (Z2) consists of intensities above lactate threshold, but below the maximal metabolic steady state (normally determined as critical speed (CS), see Jones et al. [9]), and zone 3 (Z3) comprises high-intensity exercise, where the intensity of exercise exceeds CS [10]. ...
Background
The training characteristics and training intensity distribution (TID) of elite athletes have been extensively studied, but a comprehensive analysis of the TID across runners from different performance levels is lacking.
Methods
Training sessions from the 16 weeks preceding 151,813 marathons completed by 119,452 runners were analysed. The TID was quantified using a three-zone approach (Z1, Z2 and Z3), where critical speed defined the boundary between Z2 and Z3, and the transition between Z1 and Z2 was assumed to occur at 82.3% of critical speed. Training characteristics and TID were reported based on marathon finish time.
Results
Training volume across all runners was 45.1 ± 26.4 km·week⁻¹, but the fastest runners within the dataset (marathon time 120–150 min) accumulated > three times more volume than slower runners. The amount of training time completed in Z2 and Z3 running remained relatively stable across performance levels, but the proportion of Z1 was higher in progressively faster groups. The most common TID approach was pyramidal, adopted by > 80% of runners with the fastest marathon times. There were strong, negative correlations (p < 0.01, R² ≥ 0.90) between marathon time and markers of training volume, and the proportion of training volume completed in Z1. However, the proportions of training completed in Z2 and Z3 were correlated (p < 0.01, R² ≥ 0.85) with slower marathon times.
Conclusion
The fastest runners in this dataset featured large training volumes, achieved primarily by increasing training volume in Z1. Marathon runners adopted a pyramidal TID approach, and the prevalence of pyramidal TID increased in the fastest runners.
... However, the identification of these anchors may be influenced by noteworthy variables such as initial load, load increment, stage duration, and cadence (in the case of cycling) [35]. A graded exercise test structured to a given population enables a highly individualized exercise prescription, reducing variability among individuals in performance responses, even for substantially heterogeneous groups such as cancer patients [35,36]. ...
... This highly individualized method holds significant potential in cancer studies due to the substantial heterogeneity among participants. Indeed, this approach has been shown to reduce variability in some responses, such as time to exhaustion and physiological markers as blood lactate [35,36]. ...
Background
High-intensity interval training (HIIT) performed before, during, and after cancer treatment can attenuate the adverse effects induced by anti-cancer drugs. A clear presentation and rationale of characteristics of HIIT variables is vital to produce the expected HIIT adaptations in cancer patients. However, there are concerns regarding the HIIT protocols used in the cancer literature.
Objectives
The aims were to (1) identify the characteristics of HIIT and the formats that have been prescribed, (2) analyze which anchors have been utilized to prescribe effort and pause intensity, (3) examine characteristics of the physical tests used for HIIT prescription, and (4) identify potential adverse events related to HIIT intervention.
Methods
This scoping review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) guidelines, including PubMed, Scopus, and Web of Science databases.
Results
A total of 51 studies were retrieved, and the following results were found: (1) Only 25 studies reported all four essential variables for HIIT prescription [effort intensity (effort duration): pause intensity (pause duration)]. Of these studies, 23 used active pause and employed the following prescription (on average): [84% (116 s): 39% (118 s)] when percentage of maximal aerobic power (MAP) [maximal/peak oxygen uptake (O2max/peak)/MAP] was used; [124% (161 s): 55% (142 s)] when percentage of anaerobic threshold (AT) was used; [83% (230 s): 62% (165 s)] when maximal heart rate percentage (%HRmax) was used. From these 23 studies, 12 used O2max/peak/MAP (one of the most recommended variables for HIIT prescription). Seven studies adopted the HIIT-long format, and in the remaining five studies, the format was unclear. (2) Twenty-four studies used fractions of O2max/peak or mechanical variables like MAP as anchors for prescribing effort intensity, two studies used AT, 20 studies used fractions of HRmax/heart rate reserve, two studies used rate of perceived exertion (RPE), while one used RPE and %O2peak concomitantly, and two studies utilized RPE/%HRmax concomitantly. Two studies utilized passive resting, 12 studies used %O2peak/%MAP for prescribing pause intensity, four studies used AT, seven studies used %HRmax, one study used %HRmax/%O2peak, and two studies used absolute loads. (3) Ten studies did not report the characteristics of the physical tests employed, two studies used submaximal tests, and 39 studies utilized graded exercise tests. (4) Ten studies did not report if there were adverse events associated with the exercise program, while 34 studies did not report any adverse events.
Conclusions
Only 50% of the studies provided all the necessary variables for accurate HIIT prescription, raising concerns about the replicability, comprehension, and effective application of HIIT in cancer patients. Most of the studies that reported all variables appeared to have employed the HIIT-long format. Only a few studies used more individualized anchors (e.g., AT) to prescribe HIIT-long format for cancer patients, which is considered a very heterogeneous population.
... It is worth noting that, whilst varying nomenclature is used to describe the different intensity domains in performance and health settings [26], the three-domain classification (moderate-, heavy-and severe-intensity exercise) will be referred to in the present study. Notably, TRAD approaches are evidenced to elicit marked variation in acute physiological responses and exercise tolerance [27][28][29][30][31][32][33]. As changes in V O 2max manifest in response to specific exercise-induced adaptive stimuli [34], when different stimuli are experienced by individuals over time, it is plausible that this may contribute to a portion of V O 2max response variability [19,31,35]. ...
... However, using physiological thresholds that demarcate the intensity domains as intensity anchors (Table 2) has been shown to elicit more homogeneous acute physiological responses to an exercise bout [29,32,33,36]. It is of interest to explore whether this has a positive impact on longer-term responses (i.e. ...
... However, contrary to our hypothesis, weak evidence was obtained in support of no difference in the variability of V O 2max change scores between THR and TRAD in both analyses. It has been shown that using THR approaches more effectively normalises exercise intensity among individuals compared with when using TRAD anchors, reducing the variability in exercise tolerance and eliciting more homogeneous acute physiological responses [29,32,33,36]. On the basis of the acute data presented in these studies, it was hypothesised that repeated performance of THR would manifest in a more consistent chronic stimulus across participants, resulting in reduced variation in change scores. ...
Background
It is unknown whether there are differences in maximal oxygen uptake (O2max) response when prescribing intensity relative to traditional (TRAD) anchors or to physiological thresholds (THR).
Objectives
The present meta-analysis sought to compare: (a) mean change in O2max, (b) proportion of individuals increasing O2max beyond a minimum important difference (MID) and (c) response variability in O2max between TRAD and THR.
Methods
Electronic databases were searched, yielding data for 1544 individuals from 42 studies. Two datasets were created, comprising studies with a control group (‘controlled’ studies), and without a control group (‘non-controlled’ studies). A Bayesian approach with multi-level distributional models was used to separately analyse O2max change scores from the two datasets and inferences were made using Bayes factors (BF). The MID was predefined as one metabolic equivalent (MET; 3.5 mL kg⁻¹ min⁻¹).
Results
In controlled studies, mean O2max change was greater in the THR group compared with TRAD (4.1 versus 1.8 mL kg⁻¹ min⁻¹, BF > 100), with 64% of individuals in the THR group experiencing an increase in O2max > MID, compared with 16% of individuals taking part in TRAD. Evidence indicated no difference in standard deviation of change between THR and TRAD (1.5 versus 1.7 mL kg⁻¹ min⁻¹, BF = 0.55), and greater variation in exercise groups relative to non-exercising controls (1.9 versus 1.3 mL kg⁻¹ min⁻¹, BF = 12.4). In non-controlled studies, mean O2max change was greater in the THR group versus the TRAD group (4.4 versus 3.4 mL kg⁻¹ min⁻¹, BF = 35.1), with no difference in standard deviation of change (3.0 versus 3.2 mL kg⁻¹ min⁻¹, BF = 0.41).
Conclusion
Prescribing exercise intensity using THR approaches elicited superior mean changes in O2max and increased the likelihood of increasing O2max beyond the MID compared with TRAD. Researchers designing future exercise training studies should thus consider the use of THR approaches to prescribe exercise intensity where possible. Analysis comparing interventions with controls suggested the existence of intervention response heterogeneity; however, evidence was not obtained for a difference in response variability between THR and TRAD. Future primary research should be conducted with adequate power to investigate the scope of inter-individual differences in O2max trainability, and if meaningful, the causative factors.