Supporting the prescription of exercise in spinal cord injured populations

Following a spinal cord injury (SCI), participation in regular exercise can enhance physical capacity and performance in activities of daily living. With this in mind, the use of subjective ratings of perceived exertion (RPE) may provide an easy-to-administer alternative to traditional methods of regulating exercise intensity (e.g. heart rate and power output (PO). A physically active lifestyle is also associated with a reduced risk of cardiovascular disease, in part because exercise exerts anti-inflammatory effects. Examining the plasma response of inflammation-mediating chemical messengers, known as cytokines, to traditional and novel exercise modalities may help maximise the anti-inflammatory potential of regular exercise. Participants with a cervical level SCI successfully self-regulated a 20 min bout of moderate intensity wheelchair propulsion (Chapter three). No differences in physiological or PO responses were observed during the imposed-intensity and self-regulated wheelchair propulsion in the trained population group. In a non-SCI group of novice wheelchair-users, a differentiated RPE specific to the exercising muscle mass (RPEP) was the dominant perceptual signal during submaximal wheelchair propulsion (Chapter four). The novice group successfully self-regulated a 12 min bout of moderate intensity wheelchair propulsion, comprising of a discontinuous 3 x 4 min protocol, using differentiated RPEP. In contrast, a more accurate self-regulation of light intensity wheelchair propulsion was observed when employing traditional overall RPE compared to RPEP. Following strenuous wheelchair propulsion, plasma concentrations of the inflammation-mediating cytokine interleukin-6 (IL-6) were significantly elevated in non-SCI and thoracic level SCI participants (Chapter five). Impaired sympathetic nervous system (SNS) function was associated with a reduced IL-6 response in participants with a cervical level SCI. The plasma IL-6 response to 30 min moderate intensity (60% VO2peak) arm-crank ergometry (ACE) was associated with an elevation in the anti-inflammatory cytokine IL-1 receptor antagonist (IL-1ra) independent of SNS activation (Chapter six). Light intensity ACE resulted in a small, significant plasma IL-6 response but no IL-1ra response. The addition of functional electrical stimulation-evoked lower-limb cycling to concurrent hand cycling, termed hybrid exercise, resulted in a greater plasma IL-6 response compared to moderate intensity hand cycling alone in participants with a thoracic level SCI (Chapter seven)

Current perspectives on profiling and enhancing wheelchair court-sport performance

Despite the growing interest in Paralympic sport, the evidence-base for supporting elite wheelchair sport performance remains in its infancy when compared to able-bodied (AB) sport. Subsequently, current practice is often based on theory adapted from AB guidelines, with a heavy reliance on anecdotal evidence and practitioner experience. Many principles in training prescription and performance monitoring with wheelchair athletes are directly transferable from AB practice, including the periodisation and tapering of athlete loads around competition. Yet, a consideration for the physiological consequences of an athlete’s impairment and the interface between athlete and their equipment are vital when targeting interventions to optimise in-competition performance. Researchers and practitioners are faced with the challenge of identifying and implementing reliable protocols that detect small but meaningful changes in impairment-specific physical capacities and on-court performance. Technologies to profile both linear and rotational on-court performance are an essential component of sports science support in order to understand sport-specific movement profiles and prescribe training intensities. In addition, an individualised approach to the prescription of athlete training and optimisation of the ‘wheelchair/user interface’ is required, accounting for an athlete’s anthropometrics, sports classification and positional role on court. As well as enhancing physical capacities, interventions must also focus on the integration of the athlete and their equipment as well as techniques for limiting environmental influence on performance. Taken together, the optimisation of wheelchair sport performance requires a multi-disciplinary approach based on the individual requirements of each athlete

Salivary alpha amylase not chromogranin A reflects sympathetic activity: exercise responses in elite male wheelchair athletes with or without cervical spinal cord injury

Background: Salivary alpha-amylase (sAA) and chromogranin A (sCgA) have both been suggested as non-invasive markers for sympathetic nervous system (SNS) activity. A complete cervical spinal cord injury leading to tetraplegia is accompanied with sympathetic dysfunction; the aim of this study was to establish the exercise response of these markers in this in vivo model. Methods: Twenty-six elite male wheelchair athletes (C6-C7 tetraplegia: N=8, T6-L1 paraplegia: N=10 and non spinal cord injured controls: N=8) performed treadmill exercise to exhaustion. Saliva and blood samples were taken pre, post, and 30 min post exercise and analysed for sAA, sCgA and plasma adrenaline concentration, respectively. Results: In all three subgroups, sAA and sCgA were elevated post exercise (P<0.05). Whilst sCgA was not different between subgroups, a group x time interaction for sAA explained the reduced post exercise sAA activity in tetraplegia (162±127 vs 313±99 (paraplegia) and 328±131 U∙mL-1 (controls), P=0.005). The post exercise increase in adrenaline was not apparent in tetraplegia (P=0.74). A significant correlation was found between adrenaline and sAA (r=0.60, P=0.01), but not between adrenaline and sCgA (r=0.06, P=0.79). Conclusions: The blunted post-exercise rise in sAA and adrenaline in tetraplegia implies that both reflect SNS activity to some degree. It is questionable whether sCgA should be used as a marker for SNS activity, both due to the exercise response which is not different between the subgroups and its non-significant relationship with adrenaline

Arm and intensity-matched leg exercise induce similar inflammatory responses

Introduction: The amount of active muscle mass can influence the acute inflammatory response to exercise, associated with reduced risk for chronic disease. This may affect those restricted to upper body exercise, for example due to injury or disability. The purpose of this study was to compare the inflammatory responses for arm exercise and intensity-matched leg exercise. Methods: Twelve male individuals performed three 45-min constant load exercise trials following determination of peak oxygen uptake for arm exercise (V[Combining Dot Above]O2peak A) and cycling (V[Combining Dot Above]O2peak C): (1) arm cranking exercise at 60%V[Combining Dot Above]O2peak A; (2) moderate cycling at 60%V[Combining Dot Above]O2peak C; and (3) easy cycling at 60%V[Combining Dot Above]O2peak A. Cytokine, adrenaline and flow cytometric analysis of monocyte subsets were performed before and up to 4h post exercise. Results: Plasma IL-6 increased from resting concentrations in all trials, however, post exercise concentrations were higher for arm exercise (1.73+/-1.04pg[BULLET OPERATOR]mL-1) and moderate cycling (1.73+/-0.95pg[BULLET OPERATOR]mL-1) compared with easy cycling (0.87+/-0.41pg[BULLET OPERATOR]mL-1,P<0.04). Similarly, the plasma IL-1ra concentration in the recovery period was higher for arm exercise (325+/-139pg[BULLET OPERATOR]mL-1) and moderate cycling (316+/-128pg[BULLET OPERATOR]mL-1) when compared with easy cycling (245+/-77pg[BULLET OPERATOR]mL-1,P<0.04). Arm exercise and moderate cycling induced larger increases in monocyte numbers and larger increases of the classical monocyte subset in the recovery period than easy cycling (P<0.05). The post-exercise adrenaline concentration was lowest for easy cycling (P=0.04). Conclusions: Arm exercise and cycling at the same relative exercise intensity induces a comparable acute inflammatory response; however, cycling at the same absolute oxygen uptake as arm exercise results in a blunted cytokine, monocyte and adrenaline response. Relative exercise intensity appears to be more important to the acute inflammatory response than modality, which is of major relevance for populations restricted to upper body exercise

A comparison of speed profiles during training and competition in elite wheelchair rugby players

Purpose: To investigate the speed profiles of individual training modes in comparison to wheelchair rugby (WCR) competition across player classifications. Methods: Speed profiles of fifteen international WCR players were determined using a radio-frequency based indoor tracking system. Mean and peak speed (m∙s-1), work-rest ratios, the relative time spent (%)and the number of high speed activities performed were measured across training sessions (n = 464) and international competition (n = 34). Training was classified into one of four modes: conditioning (n = 71), skill-based (n = 133), game related (n = 151) and game-simulation drills (n = 109). Game-simulation drills were further categorised by the structured duration, which were 3-minute game-clock (n = 44), 8-minute game-clock (n = 39), and 10-minute running-clock (n = 26). Players were grouped by their International Wheelchair Rugby Federation classification as either low-point (≤ 1.5; n = 8) or high-point players (≥ 2.0; n = 7). Results: Conditioning drills were shown to exceed the demands of competition, irrespective of classification (P ≤ 0.005; effect size [ES] = 0.6-2.0). Skill-based and game related drills under-represented the speed profiles of competition (P ≤ 0.005; ES = 0.5-1.1). Mean speed and work-rest ratios were significantly lower during 3- and 8-minute game simulation drills in relation to competition (P ≤ 0.039; ES = 0.5-0.7). However, no significant differences were identified between the 10-minute running-clock and competition. Conclusions: Although game-simulation drills provided the closest representation of competition, the structured duration appeared important since the 10-minute running-clock increased training specificity. Coaches can therefore modify the desired training response by making subtle changes to the format of game-simulation drills

Individualised internal and external training load relationships in elite wheelchair rugby players

Aim: The quantification and longitudinal monitoring of athlete training load (TL) provides a scientific explanation for changes in performance and helps manage injury/illness risk. The aim of the present study was to establish the relationship between measures of internal (heart rate (HR) and session RPE (sRPE)) and external TL specific to wheelchair rugby (WR). Methods: Fourteen international WR athletes (age = 29 ± 7 yrs; body mass = 58.9 ± 10.9 kg) were monitored during 18 training sessions over a 3 month period. Activity profiles were collected during each training session using a radio-frequency based indoor tracking system. External TL was quantified by total distance (m) covered as well as time spent and distance covered in a range of classification-specific arbitrary speed zones. Banister’s TRIMP, Edwards’s summated HR zone (SHRZ) and Lucia’s TRIMP methods were used to quantify physiological internal TL. sRPE was calculated as the product of session duration multiplied by perceived exertion using the Borg CR10 scale. Relationships between external and internal TL were examined using correlation coefficients and the 90% confidence intervals (90% CI). Results: sRPE (r=0.59) and all HR-based (r >0.80) methods showed large and very large relationships with the total distance covered during training sessions, respectively. Large and very large correlations (r =0.56-0.82) were also observed between all measures of internal TL and times spent and distances covered in low and moderate intensity speed zones. HR-based methods showed very large relationships with time (r=0.71-0.75) and distance (r=0.70-0.73) in the very high speed zone and a large relationship with the number of high intensity activities performed (r=0.56-0.62). Weaker relationships (r=0.32–0.35) were observed between sRPE and all measures of high intensity activity. A large variation of individual correlation co-efficient was observed between sRPE and all external TL measures. Conclusion: The current findings suggest that sRPE and HR-based internal TL measures provide a valid tool for quantifying volume of external TL during WR training but may underestimate high intensity activities. It is recommended both internal and external TL measures are employed for the monitoring of overall TL during court-based training in elite WR athletes

Individualised internal and external training load relationships in elite wheelchair rugby players

Aim: The quantification and longitudinal monitoring of athlete training load (TL) provides a scientific explanation for changes in performance and helps manage injury/illness risk. The aim of the present study was to establish the relationship between measures of internal (heart rate (HR) and session RPE (sRPE)) and external TL specific to wheelchair rugby (WR). Methods: Fourteen international WR athletes (age = 29 ± 7 yrs; body mass = 58.9 ± 10.9 kg) were monitored during 18 training sessions over a 3 month period. Activity profiles were collected during each training session using a radio-frequency based indoor tracking system. External TL was quantified by total distance (m) covered as well as time spent and distance covered in a range of classification-specific arbitrary speed zones. Banister’s TRIMP, Edwards’s summated HR zone (SHRZ) and Lucia’s TRIMP methods were used to quantify physiological internal TL. sRPE was calculated as the product of session duration multiplied by perceived exertion using the Borg CR10 scale. Relationships between external and internal TL were examined using correlation coefficients and the 90% confidence intervals (90% CI). Results: sRPE (r=0.59) and all HR-based (r >0.80) methods showed large and very large relationships with the total distance covered during training sessions, respectively. Large and very large correlations (r =0.56-0.82) were also observed between all measures of internal TL and times spent and distances covered in low and moderate intensity speed zones. HR-based methods showed very large relationships with time (r=0.71-0.75) and distance (r=0.70-0.73) in the very high speed zone and a large relationship with the number of high intensity activities performed (r=0.56-0.62). Weaker relationships (r=0.32–0.35) were observed between sRPE and all measures of high intensity activity. A large variation of individual correlation co-efficient was observed between sRPE and all external TL measures. Conclusion: The current findings suggest that sRPE and HR-based internal TL measures provide a valid tool for quantifying volume of external TL during WR training but may underestimate high intensity activities. It is recommended both internal and external TL measures are employed for the monitoring of overall TL during court-based training in elite WR athletes

Spinal cord injury level influences acute plasma caffeine responses

Purpose. To investigate the absorption curve and acute effects of caffeine at rest in individuals with no spinal cord injury (SCI), paraplegia (PARA) and tetraplegia (TETRA). Methods. Twenty-four healthy males (8 able-bodied (AB), 8 PARA and 8 TETRA) consumed 3 mg∙kg-1 caffeine anhydrous (CAF) in a fasted state. Plasma caffeine [CAF], glucose, lactate, free-fatty acid [FFA] and catecholamine concentrations were measured during a 150 min rest period. Results. Peak [CAF] was greater in TETRA (21.5 µM) compared to AB (12.2 µM) and PARA (15.1 µM), and mean peak [CAF] occurred at 70, 80 and 80 min, respectively. Moderate and large ES were revealed for TETRA compared to PARA and AB (-0.55 and -1.14, respectively) for the total area under the [CAF] versus time curve. Large inter-individual responses were apparent in SCI groups. The change in plasma catecholamine concentrations following CAF did not reach significance (p>0.05) however both adrenaline and noradrenaline concentrations were lowest in TETRA. Significant increases in [FFA] were seen over time (p0.05). Conclusion. Level of SCI influenced the caffeine absorption curve and there was large inter-individual variation within and between groups. Individual curves should be considered when using caffeine as an ergogenic aid in athletes with an SCI. The results indicate TETRA should trial low doses in training and PARA may consider consuming caffeine greater than 60 min prior to exercise performance. The study also supports caffeine’s direct effect on adipose tissue, which is not secondary to catecholamine release

Reliability and validity of subjective measures of aerobic intensity in adults with spinal cord injury: a systematic review

Objective: To systematically synthesize and appraise research regarding test-retest reliability or criterion validity of subjective measures for assessing aerobic exercise intensity in adults with spinal cord injury (SCI). Data Sources: Electronic databases (Pubmed, PsychINFO, SPORTDiscus, EMBASE and CINAHL) were searched from inception to 1-1-2016. Study Selection: Studies involving at least 50% of participants with SCI who performed an aerobic exercise test that included measurement of subjective and objective intensity based on test-retest reliability or criterion validity protocols. Data Extraction: Characteristics were extracted on study design, measures, participants, protocols, and results. Each study was evaluated for risk of bias based on strength of the study design and a quality checklist score (COnsensus-based Standards for the selection of health Measurement Instruments [COSMIN]). Data Synthesis: The seven eligible studies (one for reliability, six for validity) evaluated overall, peripheral and/or central ratings of perceived exertion on a 6-20 scale (RPE 6-20). No eligible studies were identified for other subjective intensity measures. The evidence for reliability and validity were synthesized separately for each measure, and assessed using Grading of Recommendations Assessment, Development, and Evaluation (GRADE). Overall, very low GRADE confidence ratings were established for reliability and validity evidence generalizable to the entire population with SCI and various upper-body and lower-body modalities. There was low confidence for the evidence showing that overall RPE 6-20 has acceptable validity for adults with SCI and high fitness levels performing moderate to vigorous-intensity upper-body aerobic exercise. Conclusions: Health care professionals and scientists need to be aware of the very low to low confidence in the evidence, which currently prohibits a strong clinical recommendation for the use of subjective measures for assessing aerobic exercise intensity in adults with SCI. However, a tentative, conditional recommendation regarding overall RPE 6-20 seems applicable depending on participants’ fitness level as well as the exercise intensity and modality used

Bilateral scapular kinematics, asymmetries and shoulder pain in wheelchair athletes

Background Shoulder pain is the most common complaint for wheelchair athletes. Scapular orientation and dyskinesia are thought to be associated with shoulder pathology, yet no previous studies have examined the bilateral scapula kinematics of wheelchair athletes during propulsion. Research question To examine bilateral scapular kinematics of highly trained wheelchair rugby (WR) players and any associations with self-reported shoulder pain during everyday wheelchair propulsion. Methods Ten WR players (5 with shoulder pain, 5 without) performed 2 × 3-minute bouts of exercise in their everyday wheelchair on a wheelchair ergometer at two sub-maximal speeds (3 and 6 km∙h-1). During the final minute, 3D kinematic data were collected at 100 Hz to describe scapulothoracic motion relative to each propulsion cycle. Instantaneous asymmetries in scapular orientation between dominant and non-dominant sides were also reported. Differences in scapular kinematics and propulsion asymmetries were compared across shoulders symptomatic and asymptomatic of pain. Results An internally rotated, upwardly rotated and anteriorly tilted scapula was common during wheelchair propulsion and asymmetries ≤ 14° did exist, yet minimal changes were observed across speeds. Participants with bilateral shoulder pain displayed a less upwardly rotated scapula during propulsion, however large inter-individual variability in scapular kinematics was noted. Significance Scapular asymmetries are exhibited by wheelchair athletes during wheelchair propulsion, yet these were not exacerbated by increased speed and had limited associations to shoulder pain. This suggests that propulsion kinematics of highly trained athletes may not be the primary cause of pain experienced by this population