Modelling inter-individual variability in acute and adaptive responses to interval training: insights into exercise intensity normalisation.

PURPOSE: To investigate the influence of exercise intensity normalisation on intra- and inter-individual acute and adaptive responses to an interval training programme. METHODS: Nineteen cyclists were split in two groups differing (only) in how exercise intensity was normalised: 80% of the maximal work rate achieved in an incremental test (% W ˙ max) vs. maximal sustainable work rate in a self-paced interval training session (% W ˙ max-SP). Testing duplicates were conducted before and after an initial control phase, during the training intervention, and at the end, enabling the estimation of inter-individual variability in adaptive responses devoid of intra-individual variability. RESULTS: Due to premature exhaustion, the median training completion rate was 88.8% for the % W ˙ max group, but 100% for the % W ˙ max-SP the group. Ratings of perceived exertion and heart rates were not sensitive to how intensity was normalised, manifesting similar inter-individual variability, although intra-individual variability was minimised for the % W ˙ max-SP group. Amongst six adaptive response variables, there was evidence of individual response for only maximal oxygen uptake (standard deviation: 0.027 L·min-1·week-1) and self-paced interval training performance (standard deviation: 1.451 W·week-1). However, inter-individual variability magnitudes were similar between groups. Average adaptive responses were also similar between groups across all variables. CONCLUSIONS: To normalise completion rates of interval training, % W ˙ max-SP should be used to prescribe relative intensity. However, the variability in adaptive responses to training may not reflect how exercise intensity is normalised, underlining the complexity of the exercise dose-adaptation relationship. True inter-individual variability in adaptive responses cannot always be identified when intra-individual variability is accounted for.

Conventional methods to prescribe exercise intensity are ineffective for exhaustive interval training.

PURPOSE: To compare methods of relative intensity prescription for their ability to normalise performance (i.e., time to exhaustion), physiological, and perceptual responses to high-intensity interval training (HIIT) between individuals. METHODS: Sixteen male and two female cyclists (age: 38 ± 11 years, height: 177 ± 7 cm, body mass: 71.6 ± 7.9 kg, maximal oxygen uptake ([Formula: see text]O2max): 54.3 ± 8.9 ml·kg-1 min-1) initially undertook an incremental test to exhaustion, a 3 min all-out test, and a 20 min time-trial to determine prescription benchmarks. Then, four HIIT sessions (4 min on, 2 min off) were each performed to exhaustion at: the work rate associated with the gas exchange threshold ([Formula: see text]GET) plus 70% of the difference between [Formula: see text]GET and the work rate associated with [Formula: see text]O2max; 85% of the maximal work rate of the incremental test (85%[Formula: see text]max); 120% of the mean work rate of the 20 min time-trial (120%TT); and the work rate predicted to expend, in 4 min, 80% of the work capacity above critical power. Acute HIIT responses were modelled with participant as a random effect to provide estimates of inter-individual variability. RESULTS: For all dependent variables, the magnitude of inter-individual variability was high, and confidence intervals overlapped substantially, indicating that the relative intensity normalisation methods were similarly poor. Inter-individual coefficients of variation for time to exhaustion varied from 44.2% (85%[Formula: see text]max) to 59.1% (120%TT), making it difficult to predict acute HIIT responses for an individual. CONCLUSION: The present study suggests that the methods of intensity prescription investigated do not normalise acute responses to HIIT between individuals.

Interlimb differences in parameters of aerobic function and local profiles of deoxygenation during double-leg and counterweighted single-leg cycling.

It is typically assumed that in the context of double-leg cycling, dominant (DOMLEG) and nondominant legs (NDOMLEG) have similar aerobic capacity and both contribute equally to the whole body physiological responses. However, there is a paucity of studies that have systematically investigated maximal and submaximal aerobic performance and characterized the profiles of local muscle deoxygenation in relation to leg dominance. Using counterweighted single-leg cycling, this study explored whether peak O2 consumption (V̇o2peak), maximal lactate steady-state (MLSSp), and profiles of local deoxygenation [HHb] would be different in the DOMLEG compared with the NDOMLEG. Twelve participants performed a series of double-leg and counterweighted single-leg DOMLEG and NDOMLEG ramp-exercise tests and 30-min constant-load trials. V̇o2peak was greater in the DOMLEG than in the NDOMLEG (2.87 ± 0.42 vs. 2.70 ± 0.39 L/min, P < 0.05). The difference in V̇o2peak persisted even after accounting for lean mass (P < 0.05). Similarly, MLSSp was greater in the DOMLEG than in the NDOMLEG (118 ± 31 vs. 109 ± 31 W; P < 0.05). Furthermore, the amplitude of the [HHb] signal during ramp exercise was larger in the DOMLEG than in the NDOMLEG during both double-leg (26.0 ± 8.4 vs. 20.2 ± 8.8 µM, P < 0.05) and counterweighted single-leg cycling (18.5 ± 7.9 vs. 14.9 ± 7.5 µM, P < 0.05). Additionally, the amplitudes of the [HHb] signal were highly to moderately correlated with the mode-specific V̇o2peak values (ranging from 0.91 to 0.54). These findings showed in a group of young men that maximal and submaximal aerobic capacities were greater in the DOMLEG than in the NDOMLEG and that superior peripheral adaptations of the DOMLEG may underpin these differences.NEW & NOTEWORTHY It is typically assumed that the dominant and nondominant legs contribute equally to the whole physiological responses. In this study, we found that the dominant leg achieved greater peak O2 uptake values, sustained greater power output while preserving whole body metabolic stability, and showed larger amplitudes of deoxygenation responses. These findings highlight heterogeneous aerobic capacities of the lower limbs, which have important implications when whole body physiological responses are examined.

Development of Perfectionism in Junior Athletes: A Three-Sample Study of Coach and Parental Pressure.

Perfectionism predicts cognitions, emotions, and behaviors in sport. Nonetheless, our understanding of the factors that influence its development is limited. The authors sought to address this issue by examining the role of coach and parental pressure in the development of perfectionism in sport. Using 3 samples of junior athletes (16-19 years; cross-sectional n = 212, 3-month longitudinal n = 101, and 6-month longitudinal n = 110), the authors examined relations between coach pressure to be perfect, parental pressure to be perfect, perfectionistic strivings, and perfectionistic concerns. Mini meta-analysis of the combined cross-sectional data (N = 423) showed that both coach pressure and parental pressure were positively correlated with perfectionistic strivings and perfectionistic concerns. In contrast, longitudinal analyses showed that only coach pressure predicted increased perfectionistic strivings and perfectionistic concerns over time. Overall, our findings provide preliminary evidence that coaches may play a more important role in the development of junior athletes' perfectionism than parents.

Metabolic and performance-related consequences of exercising at and slightly above MLSS.

Exercising at the maximal lactate steady state (MLSS) results in increased but stable metabolic responses. We tested the hypothesis that even a slight increase above MLSS (10 W), by altering the metabolic steady state, would reduce exercise performance capacity. Eleven trained men in our study performed: one ramp-incremental tests; two to four 30-minute constant-load cycling exercise trials to determine the PO at MLSS (MLSSp ), and ten watts above MLSS (MLSSp+10 ), which were immediately followed by a time-to-exhaustion test; and a time-to-exhaustion test with no-prior exercise. Pulmonary O2 uptake V.O2 ) and blood lactate concentration ([La- ]b ) as well as local muscle O2 extraction ([HHb]) and muscle activity (EMG) of the vastus lateralis (VL) and rectus femoris (RF) muscles were measured during the testing sessions. When exercising at MLSSp+10 , although V.O2 was stable, there was an increase in ventilatory responses and EMG activity, along with a non-stable [La- ]b response (P < 0.05). The [HHb] of VL muscle achieved its apex at MLSSp with no additional increase above this intensity, whereas the [HHb] of RF progressively increased during MLSSp+10 and achieved its apex during the time-to-exhaustion trials. Time-to-exhaustion performance was decreased after exercising at MLSSp (37.3 ± 16.4%) compared to the no-prior exercise condition, and further decreased after exercising at MLSSp+10 (64.6 ± 6.3%) (P < 0.05). In summary, exercising for 30 min slightly above MLSS led to significant alterations of metabolic responses which disproportionately compromised subsequent exercise performance. Furthermore, the [HHb] signal of VL seemed to achieve a "ceiling" at the intensity of exercise associated with MLSS.

Measuring the morphological characteristics of thoracolumbar fascia in ultrasound images: an inter-rater reliability study.

BACKGROUND: Chronic lower back pain is still regarded as a poorly understood multifactorial condition. Recently, the thoracolumbar fascia complex has been found to be a contributing factor. Ultrasound imaging has shown that people with chronic lower back pain demonstrate both a significant decrease in shear strain, and a 25% increase in thickness of the thoracolumbar fascia. There is sparse data on whether medical practitioners agree on the level of disorganisation in ultrasound images of thoracolumbar fascia. The purpose of this study was to establish inter-rater reliability of the ranking of architectural disorganisation of thoracolumbar fascia on a scale from 'very disorganised' to 'very organised'. METHODS: An exploratory analysis was performed using a fully crossed design of inter-rater reliability. Thirty observers were recruited, consisting of 21 medical doctors, 7 physiotherapists and 2 radiologists, with an average of 13.03 ± 9.6 years of clinical experience. All 30 observers independently rated the architectural disorganisation of the thoracolumbar fascia in 30 ultrasound scans, on a Likert-type scale with rankings from 1 = very disorganised to 10 = very organised. Internal consistency was assessed using Cronbach's alpha. Krippendorff's alpha was used to calculate the overall inter-rater reliability. RESULTS: The Krippendorf's alpha was .61, indicating a modest degree of agreement between observers on the different morphologies of thoracolumbar fascia.The Cronbach's alpha (0.98), indicated that there was a high degree of consistency between observers. Experience in ultrasound image analysis did not affect constancy between observers (Cronbach's range between experienced and inexperienced raters: 0.95 and 0.96 respectively). CONCLUSIONS: Medical practitioners agree on morphological features such as levels of organisation and disorganisation in ultrasound images of thoracolumbar fascia, regardless of experience. Further analysis by an expert panel is required to develop specific classification criteria for thoracolumbar fascia.

Cycling performance is superior for time-to-exhaustion versus time-trial in endurance laboratory tests.

Time-to-exhaustion (TTE) trials are used in a laboratory setting to measure endurance performance. However, there is some concern with their ecological validity compared with time-trials (TT). Consequently, we aimed to compare cycling performance in TTE and TT where the duration of the trials was matched. Seventeen trained male cyclists completed three TTE trials at 80, 100 and 105% of maximal aerobic power (MAP). On a subsequent visit they performed three TT over the same duration as the TTE. Participants were blinded to elapsed time, power output, cadence and heart rate (HR). Average TTE was 865 ± 345 s, 165 ± 98 s and 117 ± 45 s for the 80, 100 and 105% trials respectively. Average power output was higher for TTE (294 ± 44 W) compared to TT (282 ± 43 W) at 80% MAP (P < 0.01), but not at 100 and 105% MAP (P > 0.05). There was no difference in cadence, HR, or RPE for any trial (P > 0.05). Critical power (CP) was also higher when derived from TTE compared to TT (P < 0.01). It is concluded that TTE results in a higher average power output compared to TT at 80% MAP. When determining CP, TTE rather than TT protocols appear superior.

Individualised training at different intensities, in untrained participants, results in similar physiological and performance benefits.

This study compared effects of training at moderate, high, or a combination of the two intensities (mixed) on performance and physiological adaptations, when training durations were individualised. Untrained participants (n = 34) were assigned to a moderate, high, or mixed group. Maximal oxygen uptake (V̇O2max), power output at V̇O2max (MAP), time-to-exhaustion and gross efficiency were recorded before and after four weeks of cycling training (four times per week). The moderate group cycled at 60% MAP in blocks of 5 min with 1 min recovery, and training duration was individualised to 100% of pre-training time-to-exhaustion. The high group cycled at 100% MAP for 2 min with 3 min recovery, and training duration was set as the maximum number of repetitions completed in the first training session. The mixed group completed two moderate- and two high-intensity sessions each week, on alternate days. V̇O2max, MAP, and time-to-exhaustion increased after training (P < 0.05), but were not different between groups (P > 0.05). The mixed group improved their gross efficiency at 50% MAP more than the other two groups (P = 0.044) after training. When training is individualised for untrained participants, similar improvements in performance and physiological measures are found, despite marked differences in exercise intensity and total training duration.

Perfectionism predicts injury in junior athletes: Preliminary evidence from a prospective study.

According to the stress-injury model (Williams & Andersen, 1998), personality factors predisposing athletes to elevated levels of stress may increase the risk of injury. As perfectionism has been associated with chronic stress, it may be one such personality factor. So far, however, no study has investigated the relationships between perfectionism and injury utilising a prospective design. Therefore, the present study examined perfectionistic strivings, perfectionistic concerns and injury in 80 junior athletes from team and individual sports (mean age 17.1 years; range 16-19 years) over 10 months of active training. The results of logistic regression analyses showed that perfectionism positively predicted injury, but only perfectionistic concerns emerged as a significant positive predictor. The likelihood of sustaining an injury was increased by over two times for each 1 SD increase in perfectionistic concerns. The findings suggest that perfectionistic concerns may be a possible factor predisposing athletes to an increased risk of injury.

Perfectionism and training distress in junior athletes: a longitudinal investigation.

Perfectionistic athletes may train harder and for longer than non-perfectionistic athletes, leaving them susceptible to elevated levels of training distress. So far, however, no study has investigated the relationships between perfectionism and training distress, a key indicator of overtraining syndrome. Furthermore, no study has determined psychological predictors of overtraining syndrome. Using a two-wave design, the present study examined perfectionistic strivings, perfectionistic concerns and training distress in 141 junior athletes (mean age = 17.3 years, range = 16-19 years) over 3 months of active training. Multiple regression analyses were employed to test cross-sectional and longitudinal relationships between perfectionism and training distress. In all analyses, perfectionism emerged as a significant predictor, but strivings and concerns showed differential relationships. When the cross-sectional relationships were regarded, perfectionistic concerns positively predicted training distress (P < .001), whereas perfectionistic strivings negatively predicted training distress (P < .01). When the longitudinal relationships were regarded, only perfectionistic concerns predicted increases in training distress (P < .05), whereas perfectionistic strivings did not (P > .05). The findings suggest that sports scientists who wish to identify athletes at risk of overtraining syndrome may monitor athletes' perfectionistic concerns as a possible risk factor.

Pilot Testing of a Sampling Methodology for Assessing Seed Attachment Propensity and Transport Rate in a Soil Matrix Carried on Boot Soles and Bike Tires.

Land managers of natural areas are under pressure to balance demands for increased recreation access with protection of the natural resource. Unintended dispersal of seeds by visitors to natural areas has high potential for weedy plant invasions, with initial seed attachment an important step in the dispersal process. Although walking and mountain biking are popular nature-based recreation activities, there are few studies quantifying propensity for seed attachment and transport rate on boot soles and none for bike tires. Attachment and transport rate can potentially be affected by a wide range of factors for which field testing can be time-consuming and expensive. We pilot tested a sampling methodology for measuring seed attachment and transport rate in a soil matrix carried on boot soles and bike tires traversing a known quantity and density of a seed analog (beads) over different distances and soil conditions. We found % attachment rate on boot soles was much lower overall than previously reported, but that boot soles had a higher propensity for seed attachment than bike tires in almost all conditions. We believe our methodology offers a cost-effective option for researchers seeking to manipulate and test effects of different influencing factors on these two dispersal vectors.

Perfectionism and attitudes towards doping in junior athletes.

Recent theory and research suggest that perfectionism is a personal factor contributing to athletes' vulnerability to doping (using banned substances/drugs to enhance sporting performance). So far, however, no study has examined what aspects of perfectionism suggest a vulnerability in junior athletes. Employing a cross-sectional design, this study examined perfectionism and attitudes towards doping in 129 male junior athletes (mean age 17.3 years) differentiating four aspects of perfectionism: perfectionistic strivings, perfectionistic concerns, parental pressure to be perfect, and coach pressure to be perfect. In the bivariate correlations, only parental pressure showed a positive relationship with positive doping attitudes. In a multiple regression analysis controlling for the overlap between the four aspects, perfectionistic strivings additionally showed a negative relationship. Moreover, a structural equation model examining the relationships between all variables suggested that coach pressure had a negative indirect effect on attitudes towards doping via perfectionistic strivings. The findings indicate that perceived parental pressure to be perfect may be a factor contributing to junior athletes' vulnerability to doping, whereas perfectionistic strivings may be a protective factor.

Motivation Mediates the Perfectionism-Burnout Relationship: A Three-Wave Longitudinal Study With Junior Athletes.

Perfectionism in sports has been shown to predict longitudinal changes in athlete burnout. What mediates these changes over time, however, is still unclear. Adopting a self-determination theory perspective and using a three-wave longitudinal design, the current study examined perfectionistic strivings, perfectionistic concerns, autonomous motivation, controlled motivation, and athlete burnout in 141 junior athletes (mean age = 17.3 years) over 6 months of active training. When multilevel structural equation modeling was employed to test a mediational model, a differential pattern of between- and within-person relationships emerged. Whereas autonomous motivation mediated the negative relationship that perfectionistic strivings had with burnout at the between- and within-person level, controlled motivation mediated the positive relationship that perfectionistic concerns had with burnout at the between-persons level only. The present findings suggest that differences in autonomous and controlled motivation explain why perfectionism predicts changes in athlete burnout over time.

Perfectionism and Burnout in Junior Athletes: A Three-Month Longitudinal Study.

Perfectionism in sports has been shown to be associated with burnout in athletes. Whether perfectionism predicts longitudinal changes in athlete burnout, however, is still unclear. Using a two-wave cross-lagged panel design, the current study examined perfectionistic strivings, perfectionistic concerns, and athlete burnout in 101 junior athletes (mean age 17.7 years) over 3 months of active training. When structural equation modeling was employed to test a series of competing models, the best-fitting model showed opposite patterns for perfectionistic strivings and perfectionistic concerns. Whereas perfectionistic concerns predicted increases in athlete burnout over the 3 months, perfectionistic strivings predicted decreases. The present findings suggest that perfectionistic concerns are a risk factor for junior athletes contributing to the development of athlete burnout whereas perfectionistic strivings appear to be a protective factor.

The delta concept does not effectively normalise exercise responses to exhaustive interval training.

OBJECTIVES: This study was designed to quantify inter- and intra-individual variability in performance, physiological, and perceptual responses to high-intensity interval training prescribed using the percentage of delta (%Δ) method, in which the gas exchange threshold and maximal oxygen uptake (V̇O2max) are taken into account to normalise relative exercise intensity. DESIGN: Repeated-measures, within-subjects design with mixed-effects modelling. METHODS: Eighteen male and four female cyclists (age: 36 ±â€¯12 years, height: 178 ±â€¯10 cm, body mass: 75.2 ±â€¯13.7 kg, V̇O2max: 51.6 ±â€¯5.3 ml·kg-1·min-1) undertook an incremental test to exhaustion to determine the gas exchange threshold and V̇O2max as prescription benchmarks. On separate occasions, participants then completed four high-intensity interval training sessions of identical intensity (70 %Δ) and format (4-min on, 2-min off); all performed to exhaustion. Acute high-intensity interval training responses were modelled with participant as a random effect to provide estimates of inter- and intra-individual variability. RESULTS: Greater variability was generally observed at the between- compared with the within-individual level, ranging from 50 % to 89 % and from 11 % to 50 % of the total variability, respectively. For the group mean time to exhaustion of 20.3 min, inter- and intra-individual standard deviations reached 9.3 min (coefficient of variation = 46 %) and 4.5 min (coefficient of variation = 22 %), respectively. CONCLUSIONS: Due to the high variability observed, the %Δ method does not effectively normalise the relative intensity of exhaustive high-intensity interval training across individuals. The generally larger inter- versus intra-individual variability suggests that day-to-day biological fluctuations and/or measurement errors cannot explain the identified shortcoming of the method.

Validity of the Training-Load Concept.

Training load (TL) is a widely used concept in training prescription and monitoring and is also recognized as as an important tool for avoiding athlete injury, illness, and overtraining. With the widespread adoption of wearable devices, TL metrics are used increasingly by researchers and practitioners worldwide. Conceptually, TL was proposed as a means to quantify a dose of training and used to predict its resulting training effect. However, TL has never been validated as a measure of training dose, and there is a risk that fundamental problems related to its calculation are preventing advances in training prescription and monitoring. Specifically, we highlight recent studies from our research groups where we compare the acute performance decrement measured following a session with its TL metrics. These studies suggest that most TL metrics are not consistent with their notional training dose and that the exercise duration confounds their calculation. These studies also show that total work done is not an appropriate way to compare training interventions that differ in duration and intensity. We encourage scientists and practitioners to critically evaluate the validity of current TL metrics and suggest that new TL metrics need to be developed.

Variability in Submaximal Self-Paced Exercise Bouts of Different Intensity and Duration.

PURPOSE: Rating of perceived exertion (RPE) as a training-intensity prescription has been extensively used by athletes and coaches. However, individual variability in the physiological response to exercise prescribed using RPE has not been investigated. METHODS: Twenty well-trained competitive cyclists (male = 18, female = 2, maximum oxygen consumption = 55.07 [11.06] mL·kg-1·min-1) completed 3 exercise trials each consisting of 9 randomized self-paced exercise bouts of either 1, 4, or 8 minutes at RPEs of 9, 13, and 17. Within-athlete variability (WAV) and between-athletes variability (BAV) in power and physiological responses were calculated using the coefficient of variation. Total variability was calculated as the ratio of WAV to BAV. RESULTS: Increased RPEs were associated with higher power, heart rate, work, volume of expired oxygen (VO2), volume of expired carbon dioxide (VCO2), minute ventilation (VE), deoxyhemoglobin (ΔHHb) (P < .001), and lower tissue saturation index (ΔTSI%) and ΔO2Hb (oxyhaemoglobin; P < .001). At an RPE of 9, shorter durations resulted in lower VO2 (P < .05) and decreased ΔTSI%, and the ΔHHb increased as the duration increased (P < .05). At an RPE of 13, shorter durations resulted in lower VO2, VE, and percentage of maximum oxygen consumption (P < .001), as well as higher power, heart rate, ΔHHb (P < .001), and ΔTSI% (P < .05). At an RPE of 17, power (P < .001) and ΔTSI% (P < .05) increased as duration decreased. As intensity and duration increased, WAV and BAV in power, work, heart rate, VO2, VCO2, and VE decreased, and WAV and BAV in near-infrared spectroscopy increased. CONCLUSIONS: Self-paced intensity prescriptions of high effort and long duration result in the greatest consistency on both a within- and between-athletes basis.