Stephen D. Patterson

The Effect of Ischemic Preconditioning on Repeated Sprint Cycling Performance

PURPOSE Ischemic preconditioning enhances exercise performance. We tested the hypothesis that ischemic preconditioning would improve intermittent exercise in the form of a repeated sprint test during cycling ergometry. METHODS In a single-blind, crossover study, 14 recreationally active men (mean ± SD age, 22.9 ± 3.7 yr; height, 1.80 ± 0.07 m; and mass, 77.3 ± 9.2 kg) performed twelve 6-s sprints after four 5-min periods of bilateral limb occlusion at 220 mm Hg (ischemic preconditioning) or 20 mm Hg (placebo). RESULTS Ischemic preconditioning resulted in a 2.4% ± 2.2%, 2.6% ± 2.7%, and 3.7% ± 2.4% substantial increase in peak power for sprints 1, 2, and 3, respectively, relative to placebo, with no further changes between trials observed for any other sprint. Similar findings were observed in the first three sprints for mean power output after ischemic preconditioning (2.8% ± 2.5%, 2.6% ± 2.5%, and 3.4% ± 2.1%, for sprints 1, 2, and 3, respectively), relative to placebo. Fatigue index was not substantially different between trials. At rest, tissue saturation index was not different between the trials. During the ischemic preconditioning/placebo stimulus, there was a -19.7% ± 3.6% decrease in tissue saturation index in the ischemic preconditioning trial, relative to placebo. During exercise, there was a 5.4% ± 4.8% greater maintenance of tissue saturation index in the ischemic preconditioning trial, relative to placebo. There were no substantial differences between trials for blood lactate, electromyography (EMG) median frequency, oxygen uptake, or rating of perceived exertion (RPE) at any time points. CONCLUSION Ischemic preconditioning improved peak and mean power output during the early stages of repeated sprint cycling and may be beneficial for sprint sports.

Blood flow restriction training in clinical musculoskeletal rehabilitation: a systematic review and meta-analysis

Background and objective Low-load exercise training with blood flow restriction (BFR) can increase muscle strength and may offer an effective clinical musculoskeletal (MSK) rehabilitation tool. The aim of this review was to systematically analyse the evidence regarding the effectiveness of this novel training modality in clinical MSK rehabilitation. Design This is a systematic review and meta-analysis of peer-reviewed literature examining BFR training in clinical MSK rehabilitation (Research Registry; researchregistry91). Data sources A literature search was conducted across SPORTDiscus (EBSCO), PubMed and Science Direct databases, including the reference lists of relevant papers. Two independent reviewers extracted study characteristics and MSK and functional outcome measures. Study quality and reporting was assessed using the Tool for the assEssment of Study qualiTy and reporting in EXercise. Eligibility Search results were limited to exercise training studies investigating BFR training in clinical MSK rehabilitation, published in a scientific peer-reviewed journal in English. Results Twenty studies were eligible, including ACL reconstruction (n=3), knee osteoarthritis (n=3), older adults at risk of sarcopenia (n=13) and patients with sporadic inclusion body myositis (n=1). Analysis of pooled data indicated low-load BFR training had a moderate effect on increasing strength (Hedges’ g=0.523, 95% CI 0.263 to 0.784, p<0.001), but was less effective than heavy-load training (Hedges’ g=0.674, 95% CI 0.296 to 1.052, p<0.001). Conclusion Compared with low-load training, low-load BFR training is more effective, tolerable and therefore a potential clinical rehabilitation tool. There is a need for the development of an individualised approach to training prescription to minimise patient risk and increase effectiveness.

Effects of dietary nitrate, caffeine, and their combination on 20-km cycling time trial performance.

Abstract Glaister, M, Pattison, JR, Muniz-Pumares, D, Patterson, SD, and Foley, P. Effects of dietary nitrate, caffeine, and their combination on 20-km cycling time trial performance. J Strength Cond Res 29(1): 165–174, 2015—The aim of this study was to examine the acute supplementation effects of dietary nitrate, caffeine, and their combination on 20-km cycling time trial performance. Using a randomized, counterbalanced, double-blind Latin-square design, 14 competitive female cyclists (age: 31 ± 7 years; height: 1.69 ± 0.07 m; body mass: 61.6 ± 6.0 kg) completed four 20-km time trials on a racing bicycle fitted to a turbo trainer. Approximately 2.5 hours before each trial, subjects consumed a 70-ml dose of concentrated beetroot juice containing either 0.45 g of dietary nitrate or with the nitrate content removed (placebo). One hour before each trial, subjects consumed a capsule containing either 5 mg·kg−1 of caffeine or maltodextrin (placebo). There was a significant effect of supplementation on power output (p = 0.001), with post hoc tests revealing higher power outputs in caffeine (205 ± 21 W) vs. nitrate (194 ± 22 W) and placebo (194 ± 25 W) trials only. Caffeine-induced improvements in power output corresponded with significantly higher measures of heart rate (caffeine: 166 ± 12 b·min−1 vs. placebo: 159 ± 15 b·min−1; p = 0.02), blood lactate (caffeine: 6.54 ± 2.40 mmol·L−1 vs. placebo: 4.50 ± 2.11 mmol·L−1; p < 0.001), and respiratory exchange ratio (caffeine: 0.95 ± 0.04 vs. placebo: 0.91 ± 0.05; p = 0.03). There were no effects (p ≥ 0.05) of supplementation on cycling cadence, rating of perceived exertion, , or integrated electromyographic activity. The results of this study support the well-established beneficial effects of caffeine supplementation on endurance performance. In contrast, acute supplementation with dietary nitrate seems to have no effect on endurance performance and adds nothing to the benefits afforded by caffeine supplementation.

The response of plasma interleukin-6 and its soluble receptors to exercise in the cold in humans

Abstract In this study, we wished to determine whether the changes in metabolism observed during exercise in the cold are associated with changes in interleukin-6 (IL-6) and/or its soluble receptors. Eight healthy male participants performed 1 h of cycling exercise at 70% [Vdot]O2max in a control (20°C) and cold (0°C) environment. Plasma concentrations of IL-6, soluble IL-6 receptor (sIL-6R), and sgp130 were measured before exercise, at 30 and 60 min of exercise, and 60 min after exercise. Substrate oxidation was estimated through measures of pulmonary gas exchange recorded between 50 and 55 min of cycling. Exercise in the cold resulted in an increase (P < 0.05) in carbohydrate oxidation (mean 2.58 g · min−1, s = 0.49 at 20°C vs. 2.85 g · min−1, s = 0.58 at 0°C) and a decrease (P < 0.05) in fat oxidation (0.55 g · min−1, s = 0.17 at 20°C vs. 0.38 g · min−1, s = 0.16 at 0°C) compared with the control trial. Interleukin-6 concentrations were elevated (P < 0.05) after 60 min of exercise in both the cold and control trials, with no differences between trials at any instant. Neither sIL-6R nor sgp130 was affected by exercise or the environment. The alterations in carbohydrate and fat utilization during 1 h of exercise in the cold are not paralleled by changes in plasma concentrations of IL-6 or its soluble receptors.

Caffeine and Sprinting Performance: Dose Responses and Efficacy

Abstract Glaister, M, Patterson, SD, Foley, P, Pedlar, CR, Pattison, JR, and McInnes, G. Caffeine and sprinting performance: dose responses and efficacy. J Strength Cond Res 26(4): 1001–1005, 2012—The aims of this study were to evaluate the effects of caffeine supplementation on sprint cycling performance and to determine if there was a dose-response effect. Using a randomized, double-blind, placebo-controlled design, 17 well-trained men (age: 24 ± 6 years, height: 1.82 ± 0.06 m, and body mass(bm): 82.2 ± 6.9 kg) completed 7 maximal 10-second sprint trials on an electromagnetically braked cycle ergometer. Apart from trial 1 (familiarization), all the trials involved subjects ingesting a gelatine capsule containing either caffeine or placebo (maltodextrin) 1 hour before each sprint. To examine dose-response effects, caffeine doses of 2, 4, 6, 8, and 10 mg·kg bm−1 were used. There were no significant (p ≥ 0.05) differences in baseline measures of plasma caffeine concentration before each trial (grand mean: 0.14 ± 0.28 &mgr;g·ml−1). There was, however, a significant supplement × time interaction (p < 0.001), with larger caffeine doses producing higher postsupplementation plasma caffeine levels. In comparison with placebo, caffeine had no significant effect on peak power (p = 0.11), mean power (p = 0.55), or time to peak power (p = 0.17). There was also no significant effect of supplementation on pretrial blood lactate (p = 0.58), but there was a significant time effect (p = 0.001), with blood lactate reducing over the 50 minute postsupplementation rest period from 1.29 ± 0.36 to 1.06 ± 0.33 mmol·L−1. The results of this study show that caffeine supplementation has no effect on short-duration sprint cycling performance, irrespective of the dosage used.

Caffeine supplementation and peak anaerobic power output

Abstract The aim of this study was to investigate the effects of caffeine supplementation on peak anaerobic power output (Wmax). Using a counterbalanced, randomised, double-blind, placebo-controlled design, 14 well-trained men completed three trials of a protocol consisting of a series of 6-s cycle ergometer sprints, separated by 5-min passive recovery periods. Sprints were performed at progressively increasing torque factors to determine the peak power/torque relationship and Wmax. Apart from Trial 1 (familiarisation), participants ingested a capsule containing 5 mg·kg−1 of caffeine or placebo, one hour before each trial. The effects of caffeine on blood lactate were investigated using capillary samples taken after each sprint. The torque factor which produced Wmax was not significantly different (p ≥ 0.05) between the caffeine (1.15 ± 0.08 N·m·kg−1) and placebo (1.13 ± 0.10 N·m·kg−1) trials. There was, however, a significant effect (p < 0.05) of supplementation on Wmax, with caffeine producing a higher value (1885 ± 303 W) than placebo (1835 ± 290 W). Analysis of the blood lactate data revealed a significant (p < 0.05) torque factor × supplement interaction with values being significantly higher from the sixth sprint (torque factor 1.0 N·m·kg−1) onwards following caffeine supplementation. The results of this study confirm previous reports that caffeine supplementation significantly increases blood lactate and Wmax. These findings may explain why the majority of previous studies, which have used fixed-torque factors of around 0.75 N·m·kg−1 and thereby failing to elicit Wmax, have failed to find an effect of caffeine on sprinting performance.

The role of blood flow restriction training for applied practitioners: A questionnaire-based survey

ABSTRACT The purpose of the study was to investigate the current use of blood flow restriction (BFR) by practitioners during exercise/training. A questionnaire was developed and data were obtained from 250 participants, with 115 stating that they had prescribed BFR as an intervention. The most common exercise intervention used in combination with BFR was resistance exercise (99/115), followed by during passive (30/115) conditions, and during aerobic exercise (22/115). The main outcome measure for using the technique was to increase muscle mass (32.6%) followed by rehabilitation from injury (24.2%). Over half of respondents (57.4%) reported that they did not use the same cuff widths for the lower body and upper body, with varying final restriction pressures also being utilised during each different exercise modality. Most practitioners performed the technique for ~10 min each training session, 1–4 times per week. Eighty percent of practitioners rated the use of BFR as very good-excellent. The incidence rate of side effects was largest for delayed onset muscle soreness (39.2%), numbness (18.5%), fainting/dizziness (14.6%) and bruising (13.1%). These results indicate that the use of BFR training is widespread amongst practitioners; however, care should be taken to ensure that practice matches current research to ensure the safety of this technique.

Acute ischemic preconditioning does not influence high-intensity intermittent exercise performance

This study evaluated the acute effect of ischemic preconditioning (IPC) on a high-intensity intermittent exercise performance and physiological indicators in amateur soccer players. Thirteen players (21.5 ± 2 yrs) attended three trials separated by 3–5 days in a counterbalanced randomized cross-over design: IPC (4 × 5-min occlusion 220 mmHg/reperfusion 0 mmHg) in each thigh; SHAM (similar to the IPC protocol but “occlusion” at 20 mmHg) and control (seated during the same time of IPC). After 6-min of each trial (IPC, SHAM or control), the players performed the YoYo Intermittent Endurance Test level 2 (YoYoIE2). The distance covered in the YoYoIE2 (IPC 867 ± 205 m; SHAM 873 ± 212 m; control 921 ± 206 m) was not different among trials (p = 0.10), furthermore, lactate concentration and rate of perceived exertion did not differ (P > 0.05) among protocols. There were also no significant differences in either mean heart rate (HR) or peak HR (p > 0.05) for both IPC and SHAM compared to control. Therefore, we conclude that acute IPC does not influence high-intensity intermittent exercise performance in amateur soccer players and that rate of perceived exertion, heart rate and lactate do not differ between the intervention IPC, SHAM and control.

Ischemic preconditioning enhances critical power during a 3 minute all-out cycling test

ABSTRACT This study tested the hypothesis that ischemic preconditioning (IPC) would increase critical power (CP) during a 3 minute all-out cycling test. Twelve males completed two 3 minute all-out cycling tests, in a crossover design, separated by 7 days. These tests were preceded by IPC (4 x 5 minute intervals at 220 mmHg bilateral leg occlusion) or SHAM treatment (4 x 5 minute intervals at 20 mmHg bilateral leg occlusion). CP was calculated as the mean power output during the final 30 s of the 3 minute test with W′ taken as the total work done above CP. Muscle oxygenation was measured throughout the exercise period. There was a 15.3 ± 0.3% decrease in muscle oxygenation (TSI; [Tissue saturation index]) during the IPC stimulus, relative to SHAM. CP was significantly increased (241 ± 65 W vs. 234 ± 67 W), whereas W′ (18.4 ± 3.8 vs 17.9 ± 3.7 kJ) and total work done (TWD) were not different (61.1 ± 12.7 vs 60.8 ± 12.7 kJ), between the IPC and SHAM trials. IPC enhanced CP during a 3 minute all-out cycling test without impacting W′ or TWD. The improved CP after IPC might contribute towards the effect of IPC on endurance performance.

Enhanced Local Skeletal Muscle Oxidative Capacity and Microvascular Blood Flow Following 7-Day Ischemic Preconditioning in Healthy Humans

Ischemic preconditioning (IPC), which involves intermittent periods of ischemia followed by reperfusion, is an effective clinical intervention that reduces the risk of myocardial injury and confers ischemic tolerance to skeletal muscle. Repeated bouts of IPC have been shown to stimulate long-term changes vascular function, however, it is unclear what metabolic adaptations may occur locally in the muscle. Therefore, we investigated 7 days of bilateral lower limb IPC (4 × 5 min) above limb occlusion pressure (220 mmHg; n = 10), or sham (20 mmHg; n = 10), on local muscle oxidative capacity and microvascular blood flow. Oxidative capacity was measured using near-infrared spectroscopy (NIRS) during repeated short duration arterial occlusions (300 mmHg). Microvascular blood flow was assessed during the recovery from submaximal isometric plantar flexion exercises at 40 and 60% of maximal voluntary contraction (MVC). Following the intervention period, beyond the late phase of protection (72 h), muscle oxidative recovery kinetics were speeded by 13% (rate constant pre 2.89 ± 0.47 min-1 vs. post 3.32 ± 0.69 min-1; P < 0.05) and resting muscle oxygen consumption (mO2) was reduced by 16.4% (pre 0.39 ± 0.16%.s-1 vs. post 0.33 ± 0.14%.s-1; P < 0.05). During exercise, changes in deoxygenated hemoglobin (HHb) from rest to steady state were reduced at 40 and 60% MVC (16 and 12%, respectively, P < 0.05) despite similar measures of total hemoglobin (tHb). At the cessation of exercise, the time constant for recovery in oxygenated hemoglobin (O2Hb) was accelerated at 40 and 60% MVC (by 33 and 43%, respectively) suggesting enhanced reoxygenation in the muscle. No changes were reported for systemic measures of resting heart rate or blood pressure. In conclusion, repeated bouts of IPC over 7 consecutive days increased skeletal muscle oxidative capacity and microvascular muscle blood flow. These findings are consistent with enhanced mitochondrial and vascular function following repeated IPC and may be of clinical or sporting interest to enhance or offset reductions in muscle oxidative capacity.