Isometric Exercise Training and Arterial Hypertension: An Updated Review.

Hypertension is recognised as a leading attributable risk factor for cardiovascular disease and premature mortality. Global initiatives towards the prevention and treatment of arterial hypertension are centred around non-pharmacological lifestyle modification. Exercise recommendations differ between professional and scientific organisations, but are generally unanimous on the primary role of traditional aerobic and dynamic resistance exercise. In recent years, isometric exercise training (IET) has emerged as an effective novel exercise intervention with consistent evidence of reductions in blood pressure (BP) superior to that reported from traditional guideline-recommended exercise modes. Despite a wealth of emerging new data and endorsement by select governing bodies, IET remains underutilised and is not widely prescribed in clinical practice. This expert-informed review critically examines the role of IET as a potential adjuvant tool in the future clinical management of BP. We explore the efficacy, prescription protocols, evidence quality and certainty, acute cardiovascular stimulus, and physiological mechanisms underpinning its anti-hypertensive effects. We end the review with take-home suggestions regarding the direction of future IET research.

One year of isometric exercise training for blood pressure management in men: a prospective randomized controlled study.

OBJECTIVE: Isometric exercise training (IET) over 4-12 weeks is an effective antihypertensive intervention. However, blood pressure (BP) reductions are reversible if exercise is not maintained. No work to date has investigated the long-term effects of IET on resting BP. METHODS: We randomized 24 unmedicated patients with high-normal BP to a 1-year wall squat IET intervention or nonintervention control group. Resting BP and various clinically important haemodynamic variables, including heart rate (HR), stroke volume (SV), cardiac output (CO) and total peripheral resistance (TPR) were measured pre and post the 1-year study period. RESULTS: One year of IET produced statistically significant reductions in resting systolic (-8.5 ±â€Š5 mmHg, P  < 0.001) and diastolic (-7.3 ±â€Š5.8 mmHg, P  < 0.001) BP compared with the control group. There was also a significant reduction in resting HR (-4.2 ±â€Š3.7 b/min, P  = 0.009) and a significant increase in SV (11.2 ±â€Š2.8 ml, P  = 0.012), with no significant change in CO (0.12 ±â€Š2.8 l/min, P  = 0.7). TPR significantly decreased following IET (-246 ±â€Š88 dyne·s/cm 5 , P  = 0.011). Adherence to the IET sessions was 77% across all participants (3x IET sessions per week), with no participant withdrawals. CONCLUSION: This novel study supports IET as an effective long-term strategy for the management of resting BP, producing clinically important, chronic BP adaptations in patients at risk of hypertension. Importantly, this work also demonstrates impressive long-term adherence rates, further supporting the implementation of IET as a means of effective BP management in clinical populations.

Validity and reliability of RPE as a measure of intensity during isometric wall squat exercise.

BACKGROUND AND AIMS: Isometric exercise (IE), including wall squat training, has been shown to be effective at reducing resting blood pressure (BP). Rating of perceived exertion (RPE) is also widely used as an accessible additional measure of IE intensity. Despite this, no RPE scales have been specifically designed for use with IE and it is not clear whether RPE is sensitive enough to distinguish between different lower limb IE workloads. Therefore, the aims of this study were to assess the validity and reliability of RPE as a measure of IE intensity (workload) and physiological exertion (Heart rate and BP), and to examine whether RPE is able to discern differences in wall squat workload (knee angle) at a resolution of 10-degrees, as was previous shown for heart rate (HR) and BP. METHODS: Twenty-nine male participants completed eight separate isometric wall squat testing sessions, separated by a minimum of 5-h. Each session consisted of a single 2-min isometric wall squat test, at one of five randomized workloads (knee joint angles). Three of the knee angles were repeated, a second time, to allow measurements of reliability. Throughout the exercise protocol, HR and BP were recorded continuously; values for each 30-s time-point were calculated as the mean of the proceeding 5-s, and peak values for the 2-min bout were taken as the mean results for the final 5-s of the bout. In addition, mean results for the full 2-min period were calculated. RPE was collected every 30 s. Concurrent validity was assessed by correlating RPE results with the criterion measures: Knee joint angle, HR, and BP. Differences in RPE were assessed across consecutive workloads and time-points. RESULTS: There were significant increases in RPE at each consecutive wall squat workload (P<0.001) and between each consecutive 30-s time point (P<0.001). In addition, the RPE results produced a significant inverse relationship with knee angle (r=-0.79; P<0.001) and significant positive relationships with HR (r=0.53, P<0.001) and BP (systolic: r=0.77; diastolic: r=0.62; and mean arterial pressure: r=0.70, P<0.001). CONCLUSION: RPE provides a valid and reliable measure of isometric wall squat intensity, physiological exertion and can discern between knee angles with a resolution of 10°. RELEVANCE FOR PATIENTS: Patients and practitioners implementing isometric exercise training for arterial blood pressure reduction can use RPE to accurately monitor the intensity of the exercise and the physiological responses.

Validity and reliability of the 'Isometric Exercise Scale' (IES) for measuring ratings of perceived exertion during continuous isometric exercise.

Isometric exercise (IE) interventions are an effective non-medical method of reducing arterial blood pressure (BP). Current methods of prescribing and controlling isometric exercise intensity often require the use of expensive equipment and specialist knowledge. However, ratings of perceived exertion (RPE) may provide a more accessible means of monitoring exercise intensity. Therefore, the aim of this study was to assess the validity of a specific Isometric Exercise Scale (IES) during a continuous incremental IE test. Twenty-nine male participants completed four incremental isometric wall squat tests. Each test consisted of five 2-min stages of progressively increasing workload. Workload was determined by knee joint angle from 135° to 95°. The tests were continuous with no rest periods between the stages. Throughout the exercise protocol, RPE (IES and Borg's CR-10), heart rate and blood pressure were recorded. A strong positive linear relationship was found between the IES and the CR-10 (r = 0.967). Likewise, strong positive relationships between the IES and wall squat duration (r = 0.849), HR (r = 0.819) and BP (r = 0.841) were seen. Intra-class correlation coefficients and coefficients of variations for the IES ranged from r = 0.81 to 0.91 and 4.5-54%, respectively, with greater reliability seen at the higher workloads. The IES provides valid and reliable measurements of RPE, exercise intensity, and the changes in physiological measures of exertion during continuous incremental IE; as such, the IES can be used as an accessible measure of exercise intensity during IE interventions.

Ambulatory blood pressure adaptations to high-intensity interval training: a randomized controlled study.

OBJECTIVE: Hypertension remains the leading cause of cardiovascular disease and premature mortality globally. Although high-intensity interval training (HIIT) is an effective nonpharmacological intervention for the reduction of clinic blood pressure (BP), very little research exists regarding its effects on ambulatory BP. The aim of this study was to measure alterations in ambulatory and clinic BP following HIIT in physically inactive adults. METHODS: Forty-one participants (22.8 ±â€Š2.7 years) were randomly assigned to a 4-week HIIT intervention or control group. The HIIT protocol was performed on a cycle ergometer set against a resistance of 7.5% bodyweight and consisted of 3 × 30-s maximal sprints separated with 2-min active recovery. Clinic and ambulatory BP was recorded pre and post the control period and HIIT intervention. RESULTS: Following the HIIT intervention, 24-h ambulatory BP significantly decreased by 5.1 mmHg in sBP and 2.3 mmHg in dBP (P = 0.011 and 0.012, respectively), compared with the control group. In addition, clinic sBP significantly decreased by 6.6 mmHg compared with the control group (P = 0.021), with no significant changes in dBP and mean BP (mBP). Finally, 24-h ambulatory diastolic, daytime sBP, mBP and dBP, and night-time sBP and mBP variability significantly decreased post-HIIT compared with the control group. CONCLUSION: HIIT remains an effective intervention for the management of BP. Our findings support enduring BP reduction and improved BP variability, which are important independent risk factors for cardiovascular disease.

Left atrial mechanics and aortic stiffness following high intensity interval training: a randomised controlled study.

PURPOSE: High intensity interval training (HIIT) has been shown to improve important health parameters, including aerobic capacity, blood pressure, cardiac autonomic modulation and left ventricular (LV) mechanics. However, adaptations in left atrial (LA) mechanics and aortic stiffness remain unclear. METHODS: Forty-one physically inactive males and females were recruited. Participants were randomised to either a 4-week HIIT intervention (n = 21) or 4-week control period (n = 20). The HIIT protocol consisted of 3 × 30-s maximal cycle ergometer sprints with a resistance of 7.5% body weight, interspersed with 2-min of active unloaded recovery, three times per week. Speckle tracking imaging of the LA and M-Mode tracing of the aorta was performed pre and post HIIT and control period. RESULTS: Following HIIT, there was significant improvement in LA mechanics, including LA reservoir (13.9 ± 13.4%, p = 0.033), LA conduit (8.9 ± 11.2%, p = 0.023) and LA contractile (5 ± 4.5%, p = 0.044) mechanics compared to the control condition. In addition, aortic distensibility (2.1 ± 2.7 cm2 dyn-1 103, p = 0.031) and aortic stiffness index (- 2.6 ± 4.6, p = 0.041) were improved compared to the control condition. In stepwise linear regression analysis, aortic distensibility change was significantly associated with LA stiffness change R2 of 0.613 (p = 0.002). CONCLUSION: A short-term programme of HIIT was associated with a significant improvement in LA mechanics and aortic stiffness. These adaptations may have important health implications and contribute to the improved LV diastolic and systolic mechanics, aerobic capacity and blood pressure previously documented following HIIT.

Partial swing golf shots: scaled from full swing or independent technique?

During practice and competition, golfers are required to use submaximal effort to hit the ball a given distance, i.e., perform a partial shot. While the full golf swing has undergone extensive research, little has addressed partial shots and the biomechanical modifications golfers employ. This study investigates the biomechanical changes between full and partial swings, and determines if the partial swing is a scaled version of the full swing. Using a repeated measures design, 13 male golfers completed a minimum of 10 swings in the full and partial swing conditions, whilst club, ball, kinematic, and kinetic parameters were recorded. Large and statistically significant reductions in body motion (centre of pressure ellipse: 33.0%, p = 0.004, d = 2.26), combined with moderate reductions in lateral shift (25.5%, p = 0.004, d = 0.33) and smaller reductions in trunk rotation (arm to vertical at top of backswing: 14.1%, p = 0.002, d = 2.58) indicate golfers favour larger reductions in proximal measures, combined with diminished reductions as variables moved distally. Furthermore, the partial swing was not found to be a scaled version of the full swing implying a new approach to coaching practices might be considered.

Neurohumoral and ambulatory haemodynamic adaptations following isometric exercise training in unmedicated hypertensive patients.

OBJECTIVE: Hypertension remains the leading modifiable risk factor for cardiovascular disease. Isometric exercise training (IET) has been shown to be a useful nonpharmacological intervention for reducing resting blood pressure (BP). This study aimed to measure alterations in office BP, ambulatory BP, cardiac autonomic modulation and inflammatory and vascular biomarkers following a programme of IET in unmedicated hypertensive patients. METHODS: Twenty-four unmedicated stage 1 hypertensive patients (age 43.8 ±â€Š7.3 years; height, 178.1 ±â€Š7 cm; weight 89.7 ±â€Š12.8 kg) were randomly assigned in a cross-over study design, to 4-weeks of home-based IET and control period, separated by a 3-week washout period. Office and ambulatory BP, cardiac autonomic modulation, and inflammatory and vascular biomarkers were recorded pre and post-IET and control periods. RESULTS: Clinic and 24-h ambulatory BP significantly reduced following IET by 12.4/6.2 and 11.8/5.6 mmHg in SBP/DBP, respectively (P < 0.001 for both), compared with the control. The BP adaptations were associated with a significant (P = 0.018) reduction in the average real variability of 24-h ambulatory BP following IET, compared with control. Cardiac autonomic modulation improved by 11% (P < 0.001), baroreceptor reflex sensitivity improved by 47% (P < 0.001), and IL-6 and asymmetric dimethylarginine reduced by 10% (P = 0.022) and 19% (P = 0.023), respectively, which differed significantly to the control period. CONCLUSION: This is the first evidence of durable BP reduction and wider cardiovascular disease risk benefits of IET in a relevant patient population. Our findings support the role of IET as a safe and viable therapeutic and preventive intervention in the treatment of hypertension.

Cardiac autonomic and left ventricular mechanics following high intensity interval training: a randomized crossover controlled study.

Physical inactivity and sedentary behavior is associated with increased cardiovascular disease risk. Short duration high-intensity interval training (HIIT) has been shown to improve important health parameters. The aim of the present study was to assess the combined adaptations of the cardiac autonomic nervous system and myocardial functional and mechanical parameters to HIIT. Forty physically inactive and highly sedentary men completed two weeks of HIIT and control period. The HIIT protocol consisted of 3 × 30-s maximal cycle ergometer sprints against a resistance of 7.5% body weight, interspersed with 2 min of active recovery. Total power spectral density (PSD) and associated low-frequency (LF) and high-frequency (HF) power spectral components of heart rate variability were recorded. Conventional and speckle tracking echocardiography recorded left ventricular (LV) structural, functional, and mechanical parameters. HIIT produced a significant increase in total log-transformed (ln) PSD and ln HF and a significant decrease in LF/HF ratio (all P < 0.05) compared with the control period. HIIT produced significant improvements in LV diastolic function, including lateral E', estimated filling pressure (E/E' ratio), E deceleration time, and isovolumetric relaxation time ( P < 0.05 for all). Fractional shortening was the only conventional marker of LV systolic function to significantly improve ( P < 0.05). In this setting, there were significant improvements in global peak systolic strain rate, early and late diastolic strain rate, and early to late diastolic strain rate ratio, as well as apical rotation, apical systolic and diastolic rotation velocity, apical radial and circumferential strain and strain rate, LV torsion, and LV systolic and diastolic torsion velocity (all P < 0.05). A short-term program of HIIT was associated with a significant increase in cardiac autonomic modulation, demonstrated by a residual increase in cardiac vagal activity as well as significantly improved cardiac function and mechanics. This study demonstrates that HIIT may be an important stimulus to reduce the health implications associated with physical inactivity and sedentary behavior. NEW & NOTEWORTHY This is the first study to measure the combined adaptations of the cardiac autonomic nervous system and myocardial function and mechanics following high-intensity interval training (HIIT). This study demonstrates that a 2-wk HIIT intervention provides significant improvements in cardiac autonomic modulation and myocardial function and mechanics in a large cohort of young physically inactive and highly sedentary individuals. HIIT may be a powerful stimulus to reduce the health implications associated with physical inactivity and sedentary behavior.

The effects of acute carbohydrate and caffeine feeding strategies on cycling efficiency.

To assess the effect of carbohydrate and caffeine on gross efficiency (GE), 14 cyclists (V̇O2max 57.6 ± 6.3 ml.kg-1.min-1) completed 4 × 2-hour tests at a submaximal exercise intensity (60% Maximal Minute Power). Using a randomized, counter-balanced crossover design, participants consumed a standardised diet in the 3-days preceding each test and subsequently ingested either caffeine (CAF), carbohydrate (CHO), caffeine+carbohydrate (CAF+CHO) or water (W) during exercise whilst GE and plasma glucose were assessed at regular intervals (~30 mins). GE progressively decreased in the W condition but, whilst caffeine had no effect, this was significantly attenuated in both trials that involved carbohydrate feedings (W = -1.78 ± 0.31%; CHO = -0.70 ± 0.25%, p = 0.008; CAF+CHO = -0.63 ± 0.27%, p = 0.023; CAF = -1.12 ± 0.24%, p = 0.077). Blood glucose levels were significantly higher in carbohydrate ingestion conditions (CHO = 4.79 ± 0.67 mmol·L-1, p < 0.001; CAF+CHO = 5.05 ± 0.81 mmol·L-1, p < 0.001; CAF = 4.46 ± 0.75 mmol·L-1; W = 4.20 ± 0.53 mmol·L-1). Carbohydrate ingestion has a small but significant effect on exercise-induced reductions in GE, indicating that cyclists' feeding strategy should be carefully monitored prior to and during assessment.

Acute cardiac functional and mechanical responses to isometric exercise in prehypertensive males.

Isometric exercise (IE) training has been shown to reduce resting arterial blood pressure (ABP) in hypertensive, prehypertensive, and normotensive populations. However, the acute hemodynamic response of the heart to such exercise remains unclear. We therefore performed a comprehensive assessment of cardiac structure, function, and mechanics at rest and immediately post a single IE session in 26 male (age 44.8 ± 8.4 years) prehypertensive participants. Conventional echocardiography recorded standard and tissue Doppler measures of left ventricular (LV) structure and function. Speckle tracking echocardiography was used to measure LV global longitudinal, circumferential, and radial strain and strain rate. From this data, apical and basal rotation and rotational velocities, LV twist, systolic twist velocity, untwist velocity, and torsion were determined. IE led to a significant post exercise reduction in systolic (132.6 ± 5.6 vs. 109.4 ± 19.6 mmHg, P < 0.001) and diastolic (77.6 ± 9.4 vs. 58.8 ± 17.2 mmHg, P < 0.001) blood pressure, with no significant change in heart rate (62 ± 9.4 vs. 63 ± 7.5b·min-1, P = 0.63). There were significant reductions in LV end systolic diameter (3.4 ± 0.2 vs. 3.09 ± 0.3 cm, P = 0.002), LV posterior wall thickness (0.99 ± 0.1 vs. 0.9 ± 0.1 cm, P = 0.013), relative wall thickness (0.4 ± 0.06 vs. 0.36 ± 0.05, P = 0.027) estimated filling pressure (E/E' ratio 6.08 ± 1.87 vs. 5.01 ± 0.82, P = 0.006) and proportion of participants with LV concentric remodeling (30.8% vs. 7.8%, P = 0.035), and significant increases in LV ejection fraction (60.8 ± 3 vs. 68.3 ± 4%, P < 0.001), fractional shortening (31.6 ± 4.5 vs. 39.9 ± 5%, P < 0.001), cardiac output (4.3 ± 0.7 vs. 6.1 ± 1L·min-1, P < 0.001), and stroke volume (74.6 ± 11 vs. 96.3 ± 13.5 ml, P < 0.001). In this setting, there were significant increases in global longitudinal strain (-17.8 ± 2.4 vs. -20 ± 1.8%, P = 0.002) and strain rate (-0.88 ± 0.1 vs. -1.03 ± 0.1%, P < 0.001), basal rotation (-5 ± 3.5 vs. -7.22 ± 3.3°, P = 0.047), basal systolic rotational velocity (-51 ± 21.9 vs. -79.3 ± 41.3°·s-1, P = 0.01), basal diastolic rotational velocity (48.7 ± 18.9 vs. 62.3 ± 21.4°·s-1, P = 0.042), LV twist (10.4 ± 5.8 vs. 13.8 ± 5°, P = 0.049), systolic twist velocity (69.6 ± 27.5 vs. 98.8 ± 35.8°·s-1, P = 0.006), and untwist velocity (-64.2 ± 23 vs. -92.8 ± 38°·s-1, P = 0.007). These results suggest that IE improves LV function and mechanics acutely. This may in turn be partly responsible for the observed reductions in ABP following IE training programs and may have important implications for clinical populations.

The influence of training status, age, and muscle fiber type on cycling efficiency and endurance performance.

The purpose of this study was to assess the influence of age, training status, and muscle fiber-type distribution on cycling efficiency. Forty men were recruited into one of four groups: young and old trained cyclists, and young and old untrained individuals. All participants completed an incremental ramp test to measure their peak O2 uptake, maximal heart rate, and maximal minute power output; a submaximal test of cycling gross efficiency (GE) at a series of absolute and relative work rates; and, in trained participants only, a 1-h cycling time trial. Finally, all participants underwent a muscle biopsy of their right vastus lateralis muscle. At relative work rates, a general linear model found significant main effects of age and training status on GE (P < 0.01). The percentage of type I muscle fibers was higher in the trained groups (P < 0.01), with no difference between age groups. There was no relationship between fiber type and cycling efficiency at any work rate or cadence combination. Stepwise multiple regression indicated that muscle fiber type did not influence cycling performance (P > 0.05). Power output in the 1-h performance trial was predicted by average O2 uptake and GE, with standardized ß-coefficients of 0.94 and 0.34, respectively, although some mathematical coupling is evident. These data demonstrate that muscle fiber type does not affect cycling efficiency and was not influenced by the aging process. Cycling efficiency and the percentage of type I muscle fibers were influenced by training status, but only GE at 120 revolutions/min was seen to predict cycling performance.

Placebo effect of an inert gel on experimentally induced leg muscle pain.

PURPOSE: This study examined the therapeutic effects of an inert placebo gel on experimentally induced muscle pain in a sports therapy setting. It aimed to investigate the degree to which conditioned analgesia, coupled with an expectation of intervention, was a factor in subsequent analgesia. METHODS: Participants were sixteen male and eight female sports therapy students at a UK University. With institutional ethics board approval and following informed consent procedures, each was exposed to pain stimulus in the lower leg in five conditions, ie, conditioning, prebaseline, experimental (two placebo gel applications), and postbaseline. In conditioning trials, participants identified a level of pain stimulus equivalent to a perceived pain rating of 6/10. An inert placebo gel was then applied to the site with the explicit instruction that it was an analgesic. Participants were re-exposed to the pain stimulus, the level of which, without their knowledge, had been decreased, creating the impression of an analgesic effect resulting from the gel. In experimental conditions, the placebo gel was applied and the level of pain stimulus required to elicit a pain rating of 6/10 recorded. RESULTS: Following application of the placebo gel, the level of pain stimulus required to elicit a pain rating of 6/10 increased by 8.2%. Application of the placebo gel significantly decreased participant's perceptions of muscle pain (P = 0.001). CONCLUSION: Subjects' experience and expectation of pain reduction may be major factors in the therapeutic process. These factors should be considered in the sports therapeutic environment.

The effects of performing isometric training at two exercise intensities in healthy young males.

No previous studies have examined the effects of isometric training intensity upon resting blood pressure (BP). The aims of this study were (a) to compare the effects of leg isometric training, performed at two intensities, upon resting systolic-SBP, diastolic-DBP and mean arterial-MAP BP; and (b) to examine selected cardiovascular variables, in an attempt to explain any changes in resting BP following training. Thirty-three participants were randomly allocated to either control, high- (HI) or low-intensity (LI) training for 8 weeks. Participants performed 4 x 2 min exercise bouts 3x weekly. Resting BP was measured at baseline, 4-weeks and post-training. SBP, DBP and MAP fell significantly in both groups after training. Changes were -5.2 +/- 4.0, -2.6 +/- 2.9 and -2.5 +/- 2.2 mmHg [HI]; -3.7 +/- 3.7, -2.5 +/- 4.8 and -2.6 +/- 2.5 mmHg [LI] for SBP, DBP and MAP, respectively. There were no significant changes in BP at 4 weeks. No significant changes were observed in any of the other cardiovascular variables examined. These findings suggest that isometric training causes reductions in SBP, DBP and MAP at a range of exercise intensities, when it is performed over 8 weeks. Furthermore, it is possible to reduce resting BP using a much lower isometric exercise intensity than has previously been shown.

Familiarisation and reliability of sprint test indices during laboratory and field assessment.

The aim of the study was to assess the reliability of sprint performance in both field and laboratory conditions. Twenty-one male (mean ± s: 19 ± 1 years, 1.79 ± 0.07 m, 77.6 ± 7.1 kg) and seventeen female team sport players (mean ± s: 21 ± 4 years, 1.68 ± 0. 07 m, 62.7 ± 4.7 kg) performed a maximal 20-metre sprint running test on eight separate occasions. Four trials were conducted on a non-motorised treadmill in the laboratory; the other four were conducted outdoors on a hard-court training surface with time recorded by single-beam photocells. Trials were conducted in random order with no familiarisation prior to testing. There was a significant difference between times recorded during outdoor field trials (OFT) and indoor laboratory trials (ILT) using a non-motorised treadmill (3.47 ± 0.53 vs. 6.06 ±1.17s; p < 0.001). The coefficient of variation (CV) for time was 2.55-4.22% for OFT and 5.1-7.2% for ILT. During ILT peak force (420.9 ± 87.7N), mean force (147.2 ± 24.7N), peak power (1376.8 ± 451.9W) and mean power (514.8 ± 164.4W), and were measured. The CV for all ILT variables was highest during trial 1-2 comparison. The CV (95% confidence interval) for the trial 3-4 comparison yielded: 9.4% (7.7-12. 1%), 7.9% (6.4-10.2%), 10.1% (8.2-13.1%) and 6.2% (5.1-8.0%) for PF, MF, PP and MP and respectively. The results indicate that reliable data can be derived for single maximal sprint measures, using fixed distance protocols. However, significant differences in time/speed over 20-m exist between field and laboratory conditions. This is primarily due to the frictional resistance in the non- motorised treadmill. Measures of force and power during ILT require at least 3 familiarisations to reduce variability in test scores. Key pointsReliable data can be derived from single maximal sprint measures in both indoor and outdoor environments using fixed distance protocols.There may be significant time differences to complete fixed distance trials between the two environments.Measures of mean force, peak force and peak power during indoor trials may require multiple trials to reduce variability in test scores.

Effect of the rotor crank system on cycling performance.

The aim of this study was to evaluate the impact of a novel crank system on laboratory time-trial cycling performance. The Rotor system makes each pedal independent from the other so that the cranks are no longer fixed at 180°. Twelve male competitive but non-elite cyclists (mean ± s: 35 ± 7 yr, Wmax = 363 ± 38 W, VO2peak = 4.5 ± 0.3 L·min(-1)) completed 6-weeks of their normal training using either a conventional (CON) or the novel Rotor (ROT) pedal system. All participants then completed two 40.23-km time-trials on an air-braked ergometer, one using CON and one using ROT. Mean performance speeds were not different between trials (CON = 41.7 km·h(-1) vs. ROT = 41.6 km·h(-1), P > 0.05). Indeed, the pedal system used during the time-trials had no impact on any of the measured variables (power output, cadence, heart rate, VO2, RER, gross efficiency). Furthermore, the ANOVA identified no significant interaction effect between main effects (Time-trial crank system*Training crank system, P > 0.05). To the authors' knowledge, this is the first study to examine the effects of the Rotor system on endurance performance rather than endurance capacity. These results suggest that the Rotor system has no measurable impact on time-trial performance. However, further studies should examine the importance of the Rotor 'regulation point' and the suggestion that the Rotor system has acute ergogenic effects if used infrequently. Key pointsThe Rotor crank system does not improve gross efficiency in well-trained cyclists.The Rotor crank system has no measurable impact on laboratory 40.23-km time-trial performance.A 6-week period of familiarisation does not increase the effectiveness of the Rotor crank system.

Pharmacological and psychological effects of caffeine ingestion in 40-km cycling performance.

UNLABELLED: The ergogenic effects of caffeine are well documented. Research has yet to examine any psychological contribution to this effect. AIM: To explore the psychological and pharmacological effects of caffeine in laboratory cycling performance. METHOD: Fourteen male competitive cyclists performed 14 40-km time trials (eight experimental interspersed with six baseline). The experimental phase consisted of two trials for each of four experimental conditions: informed caffeine/received caffeine, informed no treatment/received caffeine, informed caffeine/received placebo, and informed no treatment/received no treatment. Conditions were nonrandomized. ANOVA was used to estimate main effects and interactions for mean values of power, heart rate, blood lactate, and maximal oxygen uptake. Probabilistic inferences for mean power were based on a smallest worthwhile change of 1.5%. RESULTS: Relative to baseline, a very likely beneficial main effect of receiving caffeine (3.5%; 95% confidence interval 1.5 to 5.5%), and a possibly beneficial main effect of being informed of caffeine (0.7%; -0.7 to 2.1%) were observed. A substantial interaction between belief and pharmacology indicated that caffeine exerted a greater effect on performance in conditions when subjects were informed that they had not ingested it, whereas belief exerted a greater influence on performance in the absence of caffeine (2.6%; -0.7 to 5.9%). A possibly harmful negative placebo (nocebo) effect was observed when subjects were correctly informed that they had ingested no caffeine (-1.9%; -4.1 to 0.3%). No clinically significant changes relative to baseline were observed in mean heart rate. Clear and substantial increases in blood lactate were evident after receipt of caffeine. Data for mean oxygen uptake were unclear. CONCLUSION: Our data support the ergogenic efficacy of caffeine but suggest that both positive and negative expectations impact performance.

Identification of placebo responsive participants in 40km laboratory cycling performance.

The placebo effect, a positive outcome resulting from the belief that a beneficial treatment has been received, is widely acknowledged but little understood. It has been suggested that placebo responsiveness, the degree to which an individual will respond to a placebo, might vary in the population. The study aimed to identify placebo-responsive participants from a previously published paper that examined the effects of caffeine and placebos on cycling performance. A quantitative model of placebo responsiveness was defined. 14 male participants were subsequently classified as either placebo responsive or non-responsive. Interviews were conducted to corroborate these classifications. Secondary quantitative analyses of performance data were conducted to identify further placebo responses. Finally, the five factor model of personality was used to explore relationships between personality and placebo responsiveness. Overall, 5 of 14 participants were classified as placebo responsive. Performance data suggested that 2 participants were placebo responsive whilst 12 were not. Interview data corroborated experimental data for these participants and for 9 of the remainder, however it suggested that the remaining 3 had experienced placebo effects. Secondary quantitative analysis revealed that performance for these 3 participants, whilst no better than for non-responsive participants, was associated with substantially increased oxygen uptake in the 2 conditions in which participants believed caffeine had been administered (7.0% ± 15.1; 95% confidence intervals -2.6 to 16.7, and 6.0% ± 15.4; -3.9 to 15.9 respectively). Finally, data suggested that the personality factors of extroversion, agreeableness, openness and neuroticism may relate to placebo responding. Placebo effects such as pain tolerance and fatigue resistance might be experienced by a percentage of participants but might not always be manifest in objective measures of performance. Key pointsBeliefs can have both positive (placebo) and negative (nocebo) effectsPlacebo effects may be experienced both objectively and subjectivelyCertain personality traits may be related to placebo respondingA multi-method approach may best elucidate placebo effects in sport.