Competitive rock climbing recently made its Olympic debut, but minimal published research exists ... more Competitive rock climbing recently made its Olympic debut, but minimal published research exists regarding training and competition strategies. Time management strategies define the structured approach climbers take in bouldering competitions to successfully obtain a “top” or a “zone” hold. During finals rounds of the International Federation of Sport Climbing bouldering competitions, climbers are allotted 240 s to complete a boulder. Variables influencing a climber’s time management strategies include their work-to-rest intervals, and the frequency of their attempts or rests. Video analysis of International Federation of Sport Climbing competitions was used to collect time management strategy data of professional climbers. Fifty-six boulders (28 female and 28 male boulders) over the 2019 International Federation of Sport Climbing season were analyzed. Time management strategies variables were compared between slab/slab-like and non-slab bouldering styles using generalized estimatin...
ABSTRACT Snowmobiling and off-road vehicle use are increasingly popular leisure activities. Motor... more ABSTRACT Snowmobiling and off-road vehicle use are increasingly popular leisure activities. Motorized recreation can occur during winter when citizens of colder climate countries experience more risk factors for mental illnesses: a reduction in natural light, outdoor time, and physical activity. Physical activity can greatly impact an individual’s mental health by reducing their susceptibility to symptoms of mental illness and improving mood or cognitive state. Recent physiological research suggests that participation in off-road motoring may be classified as moderate-intensity physical activity. This review aims to produce a conceptual argument for the potential benefits of motorized recreation on mental health by summarizing current research on the mental health effects of outdoor physical activity, time in nature, and social interaction.
Medicine & Science in Sports & Exercise, 2021
Supplemental digital content is available in the text. ABSTRACT Purpose Elite swimmers (Sw) have ... more Supplemental digital content is available in the text. ABSTRACT Purpose Elite swimmers (Sw) have lower diastolic function compared with elite runners, possibly as an adaptation to the aquatic training environment. Water polo players (WP) and artistic swimmers (AS) are exposed to the same hydrostatic pressures as Sw, but they are subject to different training intensities, postures, and hemodynamic stressors. Our purpose was to compare resting and exercising cardiac function in elite Sw, WP, and AS, to characterize the influence of training for aquatic sport on left ventricular (LV) adaptation. Methods Ninety athletes (Sw, 20M/17F; WP, 21M/9F; AS, 23F) at the 2019 Fédération Internationale de Natation World Championships volunteered for resting and stress (3 min 30% maximal isometric handgrip) echocardiographic assessment of LV global function and mechanics. Results Male Sw displayed greater resting systolic and diastolic function compared with WP; however, both groups maintained stroke volume under high-pressure handgrip stress (Sw, ∆−4% ± 12%; WP, ∆−1% ± 13%, P = 0.11). There were no differences between female Sw and WP resting LV function, but Sw demonstrated greater function over AS. During isometric handgrip, all female sport athletes maintained stroke volume (Sw, ∆3% ± 16%; WP, ∆−10% ± 11%; AS, ∆−2% ± 14%, P = 0.46), but WP had improved apical rotation (∆1.7° ± 4.5°), which was reduced in AS (∆−3.1° ± 4.5°) and maintained in Sw (∆−0.5° ± 3.8°, P = 0.04). Unlike Sw and WP, AS displayed a unique maintenance of early filling velocity during handgrip exercise (Sw, ∆−3.5 ± 14.7 cm·s−1; WP, ∆−15.1 ± 10.8 cm·s−1; AS, ∆1.5 ± 15.3 cm·s−1, P = 0.02). Conclusions Among male athletes, Sw display primarily volume-based functional adaptations distinct from the mixed volume–pressure adaptations of WP; however, both groups can maintain stroke volume with increased afterload. Female Sw and WP do not demonstrate sport-specific differences like males, perhaps owing to sex differences in adaptation, but have greater volume-based adaptations than AS. Lastly, AS display unique functional adaptations that may be driven by elevated pressures under low-volume conditions.
Ketone bodies are proposed to represent an alternative fuel source driving energy production, par... more Ketone bodies are proposed to represent an alternative fuel source driving energy production, particularly during exercise. Biologically, the extent to which mitochondria utilize ketone bodies compared to other substrates remains unknown. We demonstrate in vitro that maximal mitochondrial respiration supported by ketone bodies is low when compared to carbohydrate‐derived substrates in the left ventricle and red gastrocnemius muscle from rodents, and in human skeletal muscle. When considering intramuscular concentrations of ketone bodies and the presence of other carbohydrate and lipid substrates, biological rates of mitochondrial respiration supported by ketone bodies are predicted to be minimal. At the mitochondrial level, it is therefore unlikely that ketone bodies are an important source for energy production in cardiac and skeletal muscle, particularly when other substrates are readily available.
Medicine & Science in Sports & Exercise, 2020
PURPOSE Sprint interval training (SIT) has gained popularity as a time-effective alternative to m... more PURPOSE Sprint interval training (SIT) has gained popularity as a time-effective alternative to moderate-intensity endurance training (END). However, whether SIT is equally effective for decreasing cardiometabolic risk factors remains debatable, as many beneficial effects of exercise are thought to be transient and, unlike END, SIT is not recommended daily. Therefore, in line with current exercise recommendations, we examined the ability of SIT and END to improve cardiometabolic health in overweight/obese males. METHODS Twenty-three participants were randomized to perform 6 weeks of constant workload SIT (3d·wk, 4-6x30 s ~170%Wpeak, 2 min recovery, n=12) or END (5d·wk, 30-40 min, ~60%Wpeak, n=11) on cycle ergometers. Aerobic capacity (VO2peak), body composition, blood pressure (BP), arterial stiffness, endothelial function, glucose and lipid tolerance, and free-living glycemic regulation were assessed pre- and post-training. RESULTS Both END and SIT increased VO2peak (END ~15%, SIT ~5%) and glucose tolerance (~20%). However, only END decreased diastolic BP, abdominal fat, and improved post-prandial lipid tolerance, representing improvements in cardiovascular risk factors that did not occur following SIT. While SIT, but not END, increased endothelial function, arterial stiffness was not altered in either group. Indices of free-living glycemic regulation were improved following END and trended towards an improvement following SIT (p=0.06-0.09). However, glycemic control was better on exercise compared to rest days, highlighting the importance of exercise frequency. Furthermore, in an exploratory nature, favorable individual responses (VO2peak, BP, glucose tolerance, lipidemia, body fat) were more prevalent following END than low-frequency SIT. CONCLUSION As only high-frequency END improved BP and lipid tolerance, free-living glycemic regulation was better on days which participants exercised, and favorable individual responses were consistent following END, high-frequency END may favorably improve cardiometabolic health.
Evidence suggests blood flow restricted (BFR) resistance training performed with low-loads (20-40... more Evidence suggests blood flow restricted (BFR) resistance training performed with low-loads (20-40% 1-repetition maximum; 1-RM) is superior to low-load training when volume (load x repetitions) is matched. Since it has been shown using traditional resistance training that similar gains in muscle strength and hypertrophy occur between highand low-load training when performed to repetition failure, it is of interest if this also occurs with low-load training with/without BFR. Moreover, the perception of pain at repetition failure between protocols and over time has not been examined in a training setting. PURPOSE: To determine if low-load resistance training to repetition failure with/without BFR elicits similar muscular strength, hypertrophy and perceived pain. METHODS: Seven young (25±1 yr) males were recruited to perform single-leg Smith-machine squats 3 d/wk for 6 wk. Each leg was randomly assigned to perform 30% 1-RM with (BFR) or without BFR (RT) for 3 sets to repetition failure with 100s of rest after each set. Tourniquet pressure was set at 60-70% of the lowest occlusive pressure and remained inflated throughout the 3 sets. Leg strength (1-RM), muscle hypertrophy (leg lean mass; LLM) by dual-energy X-ray absorptiometry, and ultrasound derived vastus lateralis (VL) muscle thickness (MT), were measured before and after the 6-weeks. A visual analog scale (1000 point) was used to assess pain after each set and rest period for the 1st, 4th, 8th, 11th and 15th training session. RESULTS: 1-RM increased similarly in both groups after training (BFR 79±13 to 95±13 kg vs. RT 82±13 to 100±13 kg, p<0.002) and VL MT (BFR: 2.69±0.08 to 2.98±0.1 vs. RT: 2.75±0.16 to 2.96±0.1 cm, p<0.016) with non-significant changes in LLM (BFR 7.29±0.38 to 7.40±0.39 vs. RT 7.28±0.37 to 7.34±0.36 kg, p<0.243). There was an increase in perceived pain with BFR training compared to the RT group across all sessions following the first rest period (BFR: 288±25 vs. RT: 155±9 a.u., p<0.05) and second rest period (BFR: 433±31 vs. RT:160±9 a.u., p<0.05). While there was a trend for a decrease in pain over time with repeated training, this effect was non-significant. CONCLUSIONS: When performed to failure, low-load training with and without BFR have similar muscle strength and hypertrophy despite differences in perceived pain. Supported by NSERC, CFI and ERA
International Journal of Sports Physiology and Performance, 2019
Purpose: Ischemic preconditioning (IPC) through purposeful circulatory occlusion may enhance exer... more Purpose: Ischemic preconditioning (IPC) through purposeful circulatory occlusion may enhance exercise performance. The value of IPC for improving performance is controversial owing to challenges with employing effective placebo controls. This study examines the efficacy of IPC versus a deceptive sham protocol for improving performance to determine whether benefits of IPC are attributable to true physiological effects. It was hypothesized that IPC would favorably alter performance more than a sham treatment and that physiological responses to exercise would be affected only after IPC treatment. Methods: In a randomized order, 16 participants performed incremental exercise to exhaustion on a cycle ergometer in control conditions and after sham and IPC treatments. Participants rated their belief as to the efficacy of each treatment compared with control. Results: Time to exhaustion was greatest after IPC (control = 1331 [270] s, IPC = 1429 [300] s, sham = 1343 [255] s, P = .02), despit...
International journal of sports physiology and performance, Jan 18, 2018
Ischemic pre-conditioning (IPC) was initially developed to protect the myocardium from ischemia t... more Ischemic pre-conditioning (IPC) was initially developed to protect the myocardium from ischemia through altered cardiocyte metabolism. Due to the observed effects on metabolism and oxygen kinetics, IPC gained interest as a potential ergogenic aid in sport. Limited research evaluating the effects of IPC on maximal short-duration activities has been performed and of the existing literature, mixed outcomes resulting from intra-subject variation may have clouded the efficacy of this technique for enhancing sprint performance. Therefore, the current study employed a randomized repeated-measures crossover design with IPC, placebo (SHAM), and control conditions while using sprint-trained athletes (n=18) to determine the effect of IPC (3 x 5 min occlusions, with 5min reperfusion), concluding fifteen minutes prior to maximal 10 and 20 m sprinting. A visual analogue scale was used in conjunction with the sprint trials to evaluate any possible placebo effect on performance. Despite a "sig...
The combined effect of neuromuscular electrical muscle stimulation (NMES) and blood flow restrict... more The combined effect of neuromuscular electrical muscle stimulation (NMES) and blood flow restriction (BFR) on muscle mass and strength has not been thoroughly investigated. To examine the effects of combined and independent BFR and a low-intensity NMES on skeletal muscle adaptation. Exploratory Study. Laboratory. Twenty recreationally active subjects. Subjects had each leg randomly allocated to one of four possible intervention groups: 1) cyclic BFR alone 2) NMES alone 3) BFR+NMES (COMB), or 4) control (CON). Each leg was stimulated in its respective intervention group for 32 minutes, 4d/wk for six weeks. Mean differences in size (g) and isometric strength (kg), between week 0 and week 6, were calculated for each group. Leg strength increased 32±19 kg in the COMB group, which differed from the 3±11kg change in the CON group (p=0.03). The isolated NMES and BFR groups revealed increases of 16±28kg and 18±17kg, respectively, but these did not statistically differ from the control, or o...
We thank Drs. da Mota and Marocolo for their interest and insight [1] regarding our review on isc... more We thank Drs. da Mota and Marocolo for their interest and insight [1] regarding our review on ischemic preconditioning (IPC) and human exercise performance [2]. As raised by the authors, an important issue in this area remains the precise definition of IPC, and whether it includes any ischemia–reperfusion stimulus. As highlighted, a number of studies prior to the 1980s investigated singular bouts of ischemia on muscular work [3, 4]. However, to our knowledge, these investigations were not designed a priori to test ischemia-reperfusion as an intervention to exert adaptive physiological effects, a fundamental principal of the scientific method. Our definition of IPC was based on the first established protocol to exert cytoprotective effects [5], and more recent investigations demonstrating the requirement of multiple brief ischemic bouts [6, 7]. We do acknowledge that, should benefits exist, the specific IPC protocol required to elicit ergogenic effects may well differ from those producing cytoprotective responses. Our review emphasized the current equipoise concerning the effects of IPC on exercise performance, and attempted to look deeper than group mean statistics to quantify within-study individual responder rates. We suggested that a participant-level analysis may provide more relevant information as prior studies have found the cytoprotective effects of IPC to be lowered in aged, female, and diabetic participants [7], suggesting the existence of phenotypic IPC responder characteristics. The authors submit that the inconsistent between-study results may not be related solely to the presence of IPC responders but rather to methodological constraints of the respective study designs, most notably the limited number of placebo-controlled crossover trials. We agree with this comment and recognize their important work demonstrating improvements in both swimming [8] and resistance exercise [9] performance in recreational athletes using both IPC or a non-occlusive sham intervention compared with time controls. It is important to consider that a placebo effect relies on the assumption that participants believe (through conscious or unconscious cues) an intervention will alter outcomes [10]. The majority of the studies within our review did not report how IPC procedures were described to participants and only one study acquired knowledge of participants’ preconception of the effects of IPC on exercise performance [11], thus it is difficult to speculate on the plausibility of this effect. The current practice for sham controls most commonly employs low, non-occlusive, cuff pressures of *20 mmHg [2, 8, 9, 12] which do not share the same uncomfortable/painful stimulus as IPC [11, 13]. Whether this is perceived as beneficial or detrimental by participants unaware of the IPC protocol is unknown. In a recent attempt to control for the potential nocebo effect of IPC, 1-min blood flow occlusions (200 mmHg cuff pressure) were compared to standard non-occlusive placebo and IPC conditions [14]. The results demonstrated that 1-min blood flow occlusions elicited similar levels of discomfort to IPC but comparable exercise performance outcomes to the non-occlusive placebo condition [14], making this an attractive placebo control for future investigations. The authors also commented on the absence of data separating non-responders from those demonstrating & Philip J. Millar pmillar@uoguelph.ca
Competitive rock climbing recently made its Olympic debut, but minimal published research exists ... more Competitive rock climbing recently made its Olympic debut, but minimal published research exists regarding training and competition strategies. Time management strategies define the structured approach climbers take in bouldering competitions to successfully obtain a “top” or a “zone” hold. During finals rounds of the International Federation of Sport Climbing bouldering competitions, climbers are allotted 240 s to complete a boulder. Variables influencing a climber’s time management strategies include their work-to-rest intervals, and the frequency of their attempts or rests. Video analysis of International Federation of Sport Climbing competitions was used to collect time management strategy data of professional climbers. Fifty-six boulders (28 female and 28 male boulders) over the 2019 International Federation of Sport Climbing season were analyzed. Time management strategies variables were compared between slab/slab-like and non-slab bouldering styles using generalized estimatin...
ABSTRACT Snowmobiling and off-road vehicle use are increasingly popular leisure activities. Motor... more ABSTRACT Snowmobiling and off-road vehicle use are increasingly popular leisure activities. Motorized recreation can occur during winter when citizens of colder climate countries experience more risk factors for mental illnesses: a reduction in natural light, outdoor time, and physical activity. Physical activity can greatly impact an individual’s mental health by reducing their susceptibility to symptoms of mental illness and improving mood or cognitive state. Recent physiological research suggests that participation in off-road motoring may be classified as moderate-intensity physical activity. This review aims to produce a conceptual argument for the potential benefits of motorized recreation on mental health by summarizing current research on the mental health effects of outdoor physical activity, time in nature, and social interaction.
Medicine & Science in Sports & Exercise, 2021
Supplemental digital content is available in the text. ABSTRACT Purpose Elite swimmers (Sw) have ... more Supplemental digital content is available in the text. ABSTRACT Purpose Elite swimmers (Sw) have lower diastolic function compared with elite runners, possibly as an adaptation to the aquatic training environment. Water polo players (WP) and artistic swimmers (AS) are exposed to the same hydrostatic pressures as Sw, but they are subject to different training intensities, postures, and hemodynamic stressors. Our purpose was to compare resting and exercising cardiac function in elite Sw, WP, and AS, to characterize the influence of training for aquatic sport on left ventricular (LV) adaptation. Methods Ninety athletes (Sw, 20M/17F; WP, 21M/9F; AS, 23F) at the 2019 Fédération Internationale de Natation World Championships volunteered for resting and stress (3 min 30% maximal isometric handgrip) echocardiographic assessment of LV global function and mechanics. Results Male Sw displayed greater resting systolic and diastolic function compared with WP; however, both groups maintained stroke volume under high-pressure handgrip stress (Sw, ∆−4% ± 12%; WP, ∆−1% ± 13%, P = 0.11). There were no differences between female Sw and WP resting LV function, but Sw demonstrated greater function over AS. During isometric handgrip, all female sport athletes maintained stroke volume (Sw, ∆3% ± 16%; WP, ∆−10% ± 11%; AS, ∆−2% ± 14%, P = 0.46), but WP had improved apical rotation (∆1.7° ± 4.5°), which was reduced in AS (∆−3.1° ± 4.5°) and maintained in Sw (∆−0.5° ± 3.8°, P = 0.04). Unlike Sw and WP, AS displayed a unique maintenance of early filling velocity during handgrip exercise (Sw, ∆−3.5 ± 14.7 cm·s−1; WP, ∆−15.1 ± 10.8 cm·s−1; AS, ∆1.5 ± 15.3 cm·s−1, P = 0.02). Conclusions Among male athletes, Sw display primarily volume-based functional adaptations distinct from the mixed volume–pressure adaptations of WP; however, both groups can maintain stroke volume with increased afterload. Female Sw and WP do not demonstrate sport-specific differences like males, perhaps owing to sex differences in adaptation, but have greater volume-based adaptations than AS. Lastly, AS display unique functional adaptations that may be driven by elevated pressures under low-volume conditions.
Ketone bodies are proposed to represent an alternative fuel source driving energy production, par... more Ketone bodies are proposed to represent an alternative fuel source driving energy production, particularly during exercise. Biologically, the extent to which mitochondria utilize ketone bodies compared to other substrates remains unknown. We demonstrate in vitro that maximal mitochondrial respiration supported by ketone bodies is low when compared to carbohydrate‐derived substrates in the left ventricle and red gastrocnemius muscle from rodents, and in human skeletal muscle. When considering intramuscular concentrations of ketone bodies and the presence of other carbohydrate and lipid substrates, biological rates of mitochondrial respiration supported by ketone bodies are predicted to be minimal. At the mitochondrial level, it is therefore unlikely that ketone bodies are an important source for energy production in cardiac and skeletal muscle, particularly when other substrates are readily available.
Medicine & Science in Sports & Exercise, 2020
PURPOSE Sprint interval training (SIT) has gained popularity as a time-effective alternative to m... more PURPOSE Sprint interval training (SIT) has gained popularity as a time-effective alternative to moderate-intensity endurance training (END). However, whether SIT is equally effective for decreasing cardiometabolic risk factors remains debatable, as many beneficial effects of exercise are thought to be transient and, unlike END, SIT is not recommended daily. Therefore, in line with current exercise recommendations, we examined the ability of SIT and END to improve cardiometabolic health in overweight/obese males. METHODS Twenty-three participants were randomized to perform 6 weeks of constant workload SIT (3d·wk, 4-6x30 s ~170%Wpeak, 2 min recovery, n=12) or END (5d·wk, 30-40 min, ~60%Wpeak, n=11) on cycle ergometers. Aerobic capacity (VO2peak), body composition, blood pressure (BP), arterial stiffness, endothelial function, glucose and lipid tolerance, and free-living glycemic regulation were assessed pre- and post-training. RESULTS Both END and SIT increased VO2peak (END ~15%, SIT ~5%) and glucose tolerance (~20%). However, only END decreased diastolic BP, abdominal fat, and improved post-prandial lipid tolerance, representing improvements in cardiovascular risk factors that did not occur following SIT. While SIT, but not END, increased endothelial function, arterial stiffness was not altered in either group. Indices of free-living glycemic regulation were improved following END and trended towards an improvement following SIT (p=0.06-0.09). However, glycemic control was better on exercise compared to rest days, highlighting the importance of exercise frequency. Furthermore, in an exploratory nature, favorable individual responses (VO2peak, BP, glucose tolerance, lipidemia, body fat) were more prevalent following END than low-frequency SIT. CONCLUSION As only high-frequency END improved BP and lipid tolerance, free-living glycemic regulation was better on days which participants exercised, and favorable individual responses were consistent following END, high-frequency END may favorably improve cardiometabolic health.
Evidence suggests blood flow restricted (BFR) resistance training performed with low-loads (20-40... more Evidence suggests blood flow restricted (BFR) resistance training performed with low-loads (20-40% 1-repetition maximum; 1-RM) is superior to low-load training when volume (load x repetitions) is matched. Since it has been shown using traditional resistance training that similar gains in muscle strength and hypertrophy occur between highand low-load training when performed to repetition failure, it is of interest if this also occurs with low-load training with/without BFR. Moreover, the perception of pain at repetition failure between protocols and over time has not been examined in a training setting. PURPOSE: To determine if low-load resistance training to repetition failure with/without BFR elicits similar muscular strength, hypertrophy and perceived pain. METHODS: Seven young (25±1 yr) males were recruited to perform single-leg Smith-machine squats 3 d/wk for 6 wk. Each leg was randomly assigned to perform 30% 1-RM with (BFR) or without BFR (RT) for 3 sets to repetition failure with 100s of rest after each set. Tourniquet pressure was set at 60-70% of the lowest occlusive pressure and remained inflated throughout the 3 sets. Leg strength (1-RM), muscle hypertrophy (leg lean mass; LLM) by dual-energy X-ray absorptiometry, and ultrasound derived vastus lateralis (VL) muscle thickness (MT), were measured before and after the 6-weeks. A visual analog scale (1000 point) was used to assess pain after each set and rest period for the 1st, 4th, 8th, 11th and 15th training session. RESULTS: 1-RM increased similarly in both groups after training (BFR 79±13 to 95±13 kg vs. RT 82±13 to 100±13 kg, p<0.002) and VL MT (BFR: 2.69±0.08 to 2.98±0.1 vs. RT: 2.75±0.16 to 2.96±0.1 cm, p<0.016) with non-significant changes in LLM (BFR 7.29±0.38 to 7.40±0.39 vs. RT 7.28±0.37 to 7.34±0.36 kg, p<0.243). There was an increase in perceived pain with BFR training compared to the RT group across all sessions following the first rest period (BFR: 288±25 vs. RT: 155±9 a.u., p<0.05) and second rest period (BFR: 433±31 vs. RT:160±9 a.u., p<0.05). While there was a trend for a decrease in pain over time with repeated training, this effect was non-significant. CONCLUSIONS: When performed to failure, low-load training with and without BFR have similar muscle strength and hypertrophy despite differences in perceived pain. Supported by NSERC, CFI and ERA
International Journal of Sports Physiology and Performance, 2019
Purpose: Ischemic preconditioning (IPC) through purposeful circulatory occlusion may enhance exer... more Purpose: Ischemic preconditioning (IPC) through purposeful circulatory occlusion may enhance exercise performance. The value of IPC for improving performance is controversial owing to challenges with employing effective placebo controls. This study examines the efficacy of IPC versus a deceptive sham protocol for improving performance to determine whether benefits of IPC are attributable to true physiological effects. It was hypothesized that IPC would favorably alter performance more than a sham treatment and that physiological responses to exercise would be affected only after IPC treatment. Methods: In a randomized order, 16 participants performed incremental exercise to exhaustion on a cycle ergometer in control conditions and after sham and IPC treatments. Participants rated their belief as to the efficacy of each treatment compared with control. Results: Time to exhaustion was greatest after IPC (control = 1331 [270] s, IPC = 1429 [300] s, sham = 1343 [255] s, P = .02), despit...
International journal of sports physiology and performance, Jan 18, 2018
Ischemic pre-conditioning (IPC) was initially developed to protect the myocardium from ischemia t... more Ischemic pre-conditioning (IPC) was initially developed to protect the myocardium from ischemia through altered cardiocyte metabolism. Due to the observed effects on metabolism and oxygen kinetics, IPC gained interest as a potential ergogenic aid in sport. Limited research evaluating the effects of IPC on maximal short-duration activities has been performed and of the existing literature, mixed outcomes resulting from intra-subject variation may have clouded the efficacy of this technique for enhancing sprint performance. Therefore, the current study employed a randomized repeated-measures crossover design with IPC, placebo (SHAM), and control conditions while using sprint-trained athletes (n=18) to determine the effect of IPC (3 x 5 min occlusions, with 5min reperfusion), concluding fifteen minutes prior to maximal 10 and 20 m sprinting. A visual analogue scale was used in conjunction with the sprint trials to evaluate any possible placebo effect on performance. Despite a "sig...
The combined effect of neuromuscular electrical muscle stimulation (NMES) and blood flow restrict... more The combined effect of neuromuscular electrical muscle stimulation (NMES) and blood flow restriction (BFR) on muscle mass and strength has not been thoroughly investigated. To examine the effects of combined and independent BFR and a low-intensity NMES on skeletal muscle adaptation. Exploratory Study. Laboratory. Twenty recreationally active subjects. Subjects had each leg randomly allocated to one of four possible intervention groups: 1) cyclic BFR alone 2) NMES alone 3) BFR+NMES (COMB), or 4) control (CON). Each leg was stimulated in its respective intervention group for 32 minutes, 4d/wk for six weeks. Mean differences in size (g) and isometric strength (kg), between week 0 and week 6, were calculated for each group. Leg strength increased 32±19 kg in the COMB group, which differed from the 3±11kg change in the CON group (p=0.03). The isolated NMES and BFR groups revealed increases of 16±28kg and 18±17kg, respectively, but these did not statistically differ from the control, or o...
We thank Drs. da Mota and Marocolo for their interest and insight [1] regarding our review on isc... more We thank Drs. da Mota and Marocolo for their interest and insight [1] regarding our review on ischemic preconditioning (IPC) and human exercise performance [2]. As raised by the authors, an important issue in this area remains the precise definition of IPC, and whether it includes any ischemia–reperfusion stimulus. As highlighted, a number of studies prior to the 1980s investigated singular bouts of ischemia on muscular work [3, 4]. However, to our knowledge, these investigations were not designed a priori to test ischemia-reperfusion as an intervention to exert adaptive physiological effects, a fundamental principal of the scientific method. Our definition of IPC was based on the first established protocol to exert cytoprotective effects [5], and more recent investigations demonstrating the requirement of multiple brief ischemic bouts [6, 7]. We do acknowledge that, should benefits exist, the specific IPC protocol required to elicit ergogenic effects may well differ from those producing cytoprotective responses. Our review emphasized the current equipoise concerning the effects of IPC on exercise performance, and attempted to look deeper than group mean statistics to quantify within-study individual responder rates. We suggested that a participant-level analysis may provide more relevant information as prior studies have found the cytoprotective effects of IPC to be lowered in aged, female, and diabetic participants [7], suggesting the existence of phenotypic IPC responder characteristics. The authors submit that the inconsistent between-study results may not be related solely to the presence of IPC responders but rather to methodological constraints of the respective study designs, most notably the limited number of placebo-controlled crossover trials. We agree with this comment and recognize their important work demonstrating improvements in both swimming [8] and resistance exercise [9] performance in recreational athletes using both IPC or a non-occlusive sham intervention compared with time controls. It is important to consider that a placebo effect relies on the assumption that participants believe (through conscious or unconscious cues) an intervention will alter outcomes [10]. The majority of the studies within our review did not report how IPC procedures were described to participants and only one study acquired knowledge of participants’ preconception of the effects of IPC on exercise performance [11], thus it is difficult to speculate on the plausibility of this effect. The current practice for sham controls most commonly employs low, non-occlusive, cuff pressures of *20 mmHg [2, 8, 9, 12] which do not share the same uncomfortable/painful stimulus as IPC [11, 13]. Whether this is perceived as beneficial or detrimental by participants unaware of the IPC protocol is unknown. In a recent attempt to control for the potential nocebo effect of IPC, 1-min blood flow occlusions (200 mmHg cuff pressure) were compared to standard non-occlusive placebo and IPC conditions [14]. The results demonstrated that 1-min blood flow occlusions elicited similar levels of discomfort to IPC but comparable exercise performance outcomes to the non-occlusive placebo condition [14], making this an attractive placebo control for future investigations. The authors also commented on the absence of data separating non-responders from those demonstrating & Philip J. Millar pmillar@uoguelph.ca
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