Garry D. Wheeler

Development of Evidence-Informed Physical Activity Guidelines for Adults With Multiple Sclerosis

Most adults with multiple sclerosis (MS) are physically inactive. Physical activity guidelines are an important tool for exercise prescription, promotion, and monitoring. This article describes the application of international standards for guideline development in the creation of evidence-based physical activity guidelines for people with MS. The development process was informed by the Appraisal of Guidelines Research and Evaluation II instrument. The evidence base for the guidelines consisted of a systematic review of research examining the effects of exercise on fitness, fatigue, mobility, and health-related quality of life among people with MS. A multidisciplinary consensus panel deliberated the evidence and generated the guidelines and a preamble. Expert and stakeholder reviews of the materials led to refinement of the wording of both components of the guidelines. The resulting guidelines state that to achieve important fitness benefits, adults with MS who have mild to moderate disability need at least 30 minutes of moderate intensity aerobic activity 2 times per week and strength training exercises for major muscle groups 2 times per week. Meeting these guidelines may also reduce fatigue, improve mobility, and enhance elements of health-related quality of life. People with MS and health professionals are encouraged to adopt these rigorously developed guidelines.

The Effects of Exercise on Reproductive Function in Men

SummaryPhysical activity has a range of effects on male reproductive function depending upon the intensity and duration of the activity and the fitness of the individual. In general, it appears that relatively short, intense exercise increases serum testosterone levels, but there is debate to what degree haemoconcentration, decreased clearance and/or increased synthesis are involved. It is clear from the promptness of the testosterone increment that the mechanism does not involve gonadotrophin stimulation of the testes.There is suppression of serum testosterone levels during and subsequent to more prolonged exercise (and to some extent in the hours following intense short term exercise). Again the mechanisms are not clear: a variety of systems could influence the decrease of testosterone synthesis, including decreased gonadotrophin, increased cortisol, catecholamine or prolactin levels, or perhaps even an accumulation of metabolic waste materials.Endurance training induces changes in the function of the reproductive axis in men in a manner which appears similar to the changes in women. As in women, there is a subclinical inhibition of normal reproductive function but it is unclear whether clinical expression of reproductive suppression is common in men.The long term, physiological suppression of the hypothalamic-pituitary-gonadal axis in men is probably not of major significance but it is clear that further investigation in several areas is essential to provide continuing reassurance that ‘exercise is good for you’.

Evidence of autonomic dysreflexia during functional electrical stimulation in individuals with spinal cord injuries

The purpose of the investigation was to examine the safety and efficacy of functional electrical stimulation (FES)-assisted hydraulic resistance training in improving cardiovascular fitness in persons with spinal cord injuries. The cardiopulmonary responses of 10 high spinal cord injured (SCI) and five able bodied (AB) subjects were assessed during three bouts of FES-assisted leg extension exercise. The protocol involved three 30-minute tests: (1) unloaded leg extension, (2) hydraulically-resisted leg extension (loaded), and (3) a reproduction of the unloaded and loaded protocols to measure cardiac output (Q). Pre-measurements were made of body mass, mean limb weight, maximal force output and maximal oxygen uptake (incremental arm ergometry). Oxygen uptake (VO2), minute ventilation (Ve), respiratory exchange ratio (RER), heart rate (HR), blood pressure (BP) were recorded before, during and after tests. There was a significant difference in VO2 max between SCI and AB subjects. Cardiac output significantly increased between the loaded and unloaded tests. The significant increases from rest to unloaded and loaded exercise pointed to the potential value of adding resistance to a leg extension training regime. Heart rate and BP of the participants with SCI consistently demonstrated a response suggestive of autonomic dysreflexia. Upon stimulation an immediate increase in (predominantly systolic) BP was observed, followed by a fall in HR. On cessation of stimulation HR exhibited a substantial rebound effect and BP returned to normal levels. This response was highly reproducible and suggests caution be exercised in the use of FES for people with SCI with lesion levels above the major splanchnic outflow (T6).

THE EFFECTS OF ACUTE EXERCISE ON PULSATILE LH RELEASE IN HIGH-MILEAGE MALE RUNNERS

Evidence suggests that acute exercise and endurance training has a suppressive effect on the hypothalamic—pituitary—gonadal (HPG) axis in men and women. To determine if training and acute exercise influence the neuroendocrine regulation of the HPG axis in men we examined pulsatile LH release in six male endurance runners with a training volume of at least 80 km per week, and compared this with values in six age‐matched sedentary controls. Blood samples were obtained through an indwelling i.v. cannula from the subjects at 15‐min intervals for 6 h following 24 h without significant physical activity and again, in the runners, following 60 min of running at a speed equivalent to 5% below the anaerobic threshold. Mean LH pulse frequency and amplitude, as well as areas under the LH pulses and total LH curve, were calculated but only the mean post‐exercise area under the total LH curve area was significantly lower than basal values (P<0.05) following exercise compared with the resting values in runners. Other measures of LH release did not change with acute exercise. Basal and pre‐exercise testosterone levels were also measured and found to be at the lower end of normal men. The mean pre‐exercise serum testosterone levels were significantly higher than basal levels. Mean testosterone levels, mean pulse amplitude, and mean area under the LH curve were significantly lower in resting runners than in the controls. The data suggest that exercise induces a general lowering of LH levels but does not inhibit LH pulsatile release. An anticipatory increase in serum testosterone occurred before exercise.

Development of an indoor rowing machine with manual FES controller for total body exercise in paraplegia

Concept 2 indoor rowing machine (Concept 2 Inc., USA) was modified for functional electrical stimulation (FES) rowing exercise in paraplegia. A new seating system provides trunk stability and constrains the leg motion to the sagittal plane. A 4-channel electrical stimulator activates the quadriceps and hamstrings in Drive and Recovery phases of the rowing cycle, respectively. Two force-sensing resistors (FSR) on the handle measure the thumb press as the command signal to the electrical stimulator. Optical encoders measure the positions of the seat and handle during rowing. To synchronize the voluntarily controlled upper body movement with the FES controlled leg movement, a novel manual control system was developed. It uses the voluntary thumb presses to control the timing of the stimulation to the paralyzed leg muscles. The manual control system was intuitive and easy to learn and resulted in well-coordinated rowing. Evaluation of the modified rower by paraplegic volunteers showed that it is effective, safe, and affordable exercise alternative for paraplegics.

Testosterone, cortisol and catecholamine responses to exercise stress and autonomic dysreflexia in elite quadriplegic athletes

Episodes of short high intensity exercise are associated with an increase in circulating total testosterone (T) in men. Mechanisms may include hemoconcentration, decreased metabolic clearance and/or increased synthesis. Beta-blockade abolishes the T response suggesting a direct beta-adrenergic effect on the testes. Some spinal cord injured (SCI) athletes deliberately induce autonomic dysreflexia (boosting) to enhance performance. Associated with this practice are elevated catecholamine (CA) levels and exaggerated responses to serum catecholamine levels. Since basal T levels are reported to be normal in the SCI male, the T response to acute high intensity exercise might be expected to be exaggerated by boosting and associated elevated CA levels. The acute exercise T response has not been examined in SCI men to date. To determine whether the increased CA values associated with boosting enhanced the exercise-induced T elevation we measured circulating levels of T, Cortisol (C), norepinephrine (NE) and epinephrine (E) before and after maximal exertion and a simulated 7.5 km race with and without boosting in eight elite quadriplegic athletes. Maximal incremental exercise and a simulated 7.5 km race resulted in a rise in T similar to able bodied men under normal exercise conditions. Under boosted conditions the rise in T was eliminated while NE levels were significantly elevated above unboosted levels. The data may suggest an inhibitory role for CA on T production or release under conditions of extreme stress. Other possible mechanisms include C induced suppression, impaired gonadotropin stimulation of the Leydig cell and CA mediated alterations in gonadal blood supply.

Physical Activity, Nutrition, and Reproduction

Thin high mileage female and male runners often have reproductive problems. Strenuous physical activity can affect the hypothalamic-pituitary-gonadal (HPG) axis function of both females and males but physical activity alone probably does not cause reproductive problems. Nutritional changes and changes in the metabolic balance are likely responsible for the exercise-associated reproductive problems. Reproductive dysfunction in female athletes include pubertal delay (age at menarche 15.5 years for ballet dancers 15 years for athletes trained before menarche vs. 12.5 years for controls) luteal phase inadequacy anovulatory cycles secondary amenorrhea and oligomenorrhea. Male athletes tend to have reduced circulating testosterone androstenedione and luteinizing hormone levels. Endurance training has comparable chronic effects on the HPG axis in women and men. A possible mechanism of inhibition is changes to the gonadotropin releasing hormone-gonadotropin axis the cause of the changes is unknown. Neurotransmitter precursor deficiencies changes in thyroid function activation of stress hormones changes in glucoregulatory and other metabolic hormones changes in steroid metabolism in fat tissue changes in hepatic metabolism of binding proteins or an exaggerated peripheral response to exercise in a nutritionally stressed person are possible causes of the changes to the axis. Factors in the emergence of exercise-associated menstrual dysfunction include the physical and emotional stress of training and/or competition predisposition to menstrual irregularity inadequate nutrition weight loss and low body fat. Reduced physical activity reverses menstrual dysfunction. Further research is needed to clarify the relative importance of dietary deficiencies energy balance and physical activity in bringing about reproductive change and dysfunction. Obstacles to resolving the complex interrelationships are imprecision of dietary evaluation difficulty of accuracy versus freedom in energy balance measurements and the conceptual barrier of the body fat theory.

Electrical stimulation-assisted rowing exercise in spinal cord injured people. A pilot study

Recently a FES (functional electrical stimulation)-assisted rowing machine was developed to enhance cardiovascular training in people with spinal cord injuries. The machine was assessed in terms of its efficacy as a training tool. Six patients who were quadriplegic (C6–T1) and 2 who were paraplegic (T3–6) completed a series of three tests in succession: (1) leg stimulation only (quadriceps and hamstring groups)—‘Stim’, (2) arm row only—‘Row’ and (3) simultaneous row and stimulation—‘R & S’. Measurements recorded included oxygen uptake (VO2), minute ventilation (Ve), respiratory exchange ratio (RER), heart rate (HR) and blood pressure (BP). In addition, 6 out of the 8 subjects took part in a qualitative assessment comprising a guided interview exploring the subjects perception of the machine and test.Significant increases in VO2 were demonstrated between the three tests with R & S producing mean steady-state values of 16.34 nm (± 0.74) ml/kg/min (83% of maximum). These values represented a 12% increase over Row alone. Of interest was the qualitative assessment which revealed that subjects perceived R & S to be easier than Row despite the higher levels of VO2 observed. The results suggest that the rowing machine represents a potentially valuable hybrid training device that may significantly reduce risk factors for cardiovascular disease and improve the quality of life of people with SCI.

Cardiorespiratory responses during arm ergometry, functional electrical stimulation cycling, and two hybrid exercise conditions in spinal cord injured

Purpose. The purpose of this study was to compare peak functional aerobic power (VO2 peak) across four different types of exercise: arm crank ergometry (ACE), functional electrical stimulation (FES) cycling, and two hybrid exercise conditions: FES cycling combined with ACE and FES rowing using a newly developed rowing device (ROWSTIM). Methods. Five participants (C7 – T12), four male paraplegics with neurologically complete spinal cord injury (SCI), and one male with neurologically incomplete SCI, underwent a progressive maximal peak oxygen exercise test to ascertain peak physical work capacity during arm cranking, FES cycling, FES cycling combined with arm cranking and FES rowing. Results. Metabolic variables were significantly lower for FES cycling versus ACE, FES cycling combined with ACE and FES rowing measures (P < 0.05). However there were no significant differences between ACE, FES cycling combined with ACE and FES rowing. Conclusions. Preliminary results suggest that the ROWSTIM is as effective an exercise device or training tool for persons with SCI as ACE or combined FES-cycling and ACE, and more effective than FES-cycling. A larger sample size and further technological developments of the ROWSTIM are needed to demonstrate the efficacy of rowing over other hybrid exercise modalities and ACE.

Efficacy of rowing, backward wheeling and isolated scapular retractor exercise as remedial strength activities for wheelchair users: Application of electromyography

Shoulder dysfunction due to regular wheelchair use is a common problem among people with spinal cord injuries. As a remedial measure, strengthening of the scapular retractor muscles has been suggested. Electromyographical analysis was utilized to examine scapular retraction muscle use during rowing, backward wheeling and a standardized scapular retraction exercise in seven people with spinal cord injuries and seven able bodied subjects. In addition, a pilot study using indwelling electrodes was completed to validate the use and placement of surface electrodes. Both rowing and the standardized scapular retraction exercise recruited higher levels of retractor involvement than backward wheeling. We suggest that rowing, because of its value as a cardiovascular exercise and high level of retractor recruitment, is an appropriate and effective means of remediating scapular retractor weakness.