Martin D. Hoffman

Cardiorespiratory fitness and training in quadriplegics and paraplegics.

SummaryWith the growing interest in exercise and sport and the significance of cardiovascular disease in the spinal cord injured population, the role of endurance training in improving cardiovascular health is of particular interest. Ordinary daily activities of those with spinal cord injury are usually not adequate to maintain cardiovascular fitness, and lack of participation in a regular activity programme may result in a debilitative cycle. As this occurs, there is a reduction in functional work capacity which may limit independence, and the reduction in cardiovascular fitness may increase the risk for cardiovascular disease. Work capacity in those with spinal cord injury is limited by loss of functional muscle mass and sympathetic control. Sympathetic nervous system impairment limits control of regional blood flow and cardiac output, and maximum heart rate following cervical lesions may be reduced to 110 to 130 beats/min. However, endurance training in quadriplegics and paraplegics can elicit improvements in exercise performance similar to those observed in able-bodied individuals. Review of 13 cardiorespiratory training studies involving spinal cord injured subjects revealed average improvements of 20% in V̇O2 max and 40% in physical work capacity after 4 to 20 weeks of training. Based upon the positive results of these studies, the general endurance training guidelines for the normal population appear to also be appropriate for the spinal cord injured population. These guidelines can be followed during participation in a number of different activities and sports including wheelchair pushing, arm crank ergometry, aerobic swimming, ambulation training, canoeing and wheelchair basketball. There is no evidence that intense training and competition is harmful, but special areas of risk as a result of impairments in sensation, cardiovascular function, autonomic function and temperature regulation must be considered. The long term benefits of endurance training in those with spinal cord injury has not been adequately studied, but there is suggestion that similar physiological and psychological changes may occur as in able-bodied individuals.

Historical analysis of participation in 161 km ultramarathons in North America.

Participation trends in 100 m (161 km) ultramarathon running competitions in North America were examined from race results from 1977 through 2008. A total of 32, 352 finishes accounted for by 9815 unique individuals were identified. The annual number of races and number of finishes increased exponentially over the study period. This growth in number of finishes occurred through a combination of (1) an increase in participation among runners ≥40 years of age from less than 40% of the finishes prior to the mid-1980s to 65–70% of the finishes since 1996, (2) a growth (p < 0.0001) in participation among women from virtually none in the late 1970s to nearly 20% since 2004, and (3) an increase in the average annual number of races completed by each individual to 1.3. While there has been considerable growth in participation, the 161 km ultramarathon continues to attract a relatively small number of participants compared with running races of shorter distances.

The Western States 100-Mile Endurance Run: Participation and Performance Trends

PURPOSE Examine changes in demographics of participants and performance trends at the Western States 100-Mile Endurance Run (WSER) since its inception in 1974. METHODS Name, age, sex, and finish information was obtained on runners in the WSER from 1974 to 2007. Linear regression analyses, ANOVA, and t-tests were used to examine participation and performance trends. RESULTS The mean age of participants increased (P < 0.001) to around 45 yr, with men being an average of 3 yr older (P < 0.001) than women. The increase in average age of starters was accounted for by the growth in participation among women >or=40 yr and men >or=50 yr, and by the decreasing participation among men <50 yr. Between 1986 and 2007, there was an increasing participation among women to around 20% of all starters. With this came improved (P < 0.01) finish times for the top 5 overall women and the top 5 women in the 30-39 and 40-49 yr age groups, whereas performances among the men did not improve over this time span. Average ages of the top performers increased (P <or= 0.002) since 1990 to the upper 30s for both sexes, but the fastest times among men were comparable across the 30-39 and 40-49 yr age groups. CONCLUSIONS Participation in the WSER has increased among women and older athletes, and the ages of the fastest runners at the WSER have gradually risen to the extent that these runners are older than the ages at which the fastest marathons are run. In contrast to what has been observed for men, finish times have improved for the top women across the last two decades at the WSER.

Dilatation and Dysfunction of the Right Ventricle Immediately After Ultraendurance Exercise Exploratory Insights From Conventional Two-Dimensional and Speckle Tracking Echocardiography

Background— Running an ultramarathon has been shown to have a transient negative effect on right ventricular (RV) and left ventricular (LV) function. Additionally, recent findings suggested that ultraendurance athletes may be more at risk of developing a RV cardiomyopathy. The standard echocardiographic assessment of RV function is problematic; however, the introduction of ultrasonic speckle tracking technology has the potential to yield a comprehensive evaluation of RV longitudinal function, providing new insights into this phenomenon. Thus, the primary aim of this exploratory study was to evaluate comprehensively RV structure and function after a 161-km ultramarathon and establish whether changes in the RV are associated with alterations in LV function. Methods and Results— Myocardial speckle tracking echocardiograms of the RV and LV were obtained before and immediately after a 161-km ultramarathon in 16 healthy adults. Standard echocardiography was used to determine RV size and function and LV eccentricity index. Speckle tracking was used to determine the temporal evaluation of indices of RV and LV function. RV size was significantly increased postrace (RV outflow, 32 to 35 mm, P =0.002; RV inflow, 42 to 45 mm, P =0.027) with an increase in LV eccentricity index (1.03 to 1.13, P =0.006). RV strain (e) was significantly reduced postrace (−27% to −24%, P =0.004), but there was no change in the rates of e. Peak e in all planes of LV motion were reduced postrace (longitudinal, −18.3 to −16.3%, P =0.012; circumferential, −20.2% to −15.7%, P =0.001; radial, 53.4% to 40.3%, P =0.009). Changes in RV size and function correlated with diastolic strain rates in the LV. Conclusions— This exploratory study demonstrates RV dilatation and reduction in function after an ultramarathon. Further research is warranted to elucidate the mechanisms responsible for these findings. It is not clear what clinical impact might result from consecutive bouts of postexercise RV dysfunction.Background— Running an ultramarathon has been shown to have a transient negative effect on right ventricular (RV) and left ventricular (LV) function. Additionally, recent findings suggested that ultraendurance athletes may be more at risk of developing a RV cardiomyopathy. The standard echocardiographic assessment of RV function is problematic; however, the introduction of ultrasonic speckle tracking technology has the potential to yield a comprehensive evaluation of RV longitudinal function, providing new insights into this phenomenon. Thus, the primary aim of this exploratory study was to evaluate comprehensively RV structure and function after a 161-km ultramarathon and establish whether changes in the RV are associated with alterations in LV function. Methods and Results— Myocardial speckle tracking echocardiograms of the RV and LV were obtained before and immediately after a 161-km ultramarathon in 16 healthy adults. Standard echocardiography was used to determine RV size and function and LV eccentricity index. Speckle tracking was used to determine the temporal evaluation of indices of RV and LV function. RV size was significantly increased postrace (RV outflow, 32 to 35 mm, P=0.002; RV inflow, 42 to 45 mm, P=0.027) with an increase in LV eccentricity index (1.03 to 1.13, P=0.006). RV strain (&egr;) was significantly reduced postrace (−27% to −24%, P=0.004), but there was no change in the rates of &egr;. Peak &egr; in all planes of LV motion were reduced postrace (longitudinal, −18.3 to −16.3%, P=0.012; circumferential, −20.2% to −15.7%, P=0.001; radial, 53.4% to 40.3%, P=0.009). Changes in RV size and function correlated with diastolic strain rates in the LV. Conclusions— This exploratory study demonstrates RV dilatation and reduction in function after an ultramarathon. Further research is warranted to elucidate the mechanisms responsible for these findings. It is not clear what clinical impact might result from consecutive bouts of postexercise RV dysfunction.

Performance Trends in 161-km Ultramarathons

This report documents performance-related trends in 100-mile (161-km) ultramarathon running competitions in North America. A retrospective analysis of results from 1977 through 2008 revealed that annual finish rates increased initially and then plateaued by the early 1990s at nearly 60%. The fastest times were produced by the 30-39 year age group among the men and the 40-49 year age group for the women. Finish times of women improved relative to men through the 1980s, but were then stable over the past two decades with the fastest women running about 20% slower than the fastest men. Additionally, the average times of the fastest runners did not change over the past two decades for any age group for either sex. The percentage difference in finish times between the first and fifth place runners has remained lower (p<0.0001) for men than women, and has shown an upward trend (p=0.003) across time for men. It is concluded that increasing participation in 161-km ultramarathons in North America has not been associated with improvements in performance or depth of competition with the exception of the relative improvements in finish times for women compared with men that was evident through the 1980s.

Experimentally induced pain perception is acutely reduced by aerobic exercise in people with chronic low back pain

This study examined whether subjects with chronic low back pain demonstrate exercise-induced analgesia to experimentally induced pressure pain. We employed a repeated measures design to study eight subjects with chronic low back pain (mean +/- standard deviation age = 40 +/- 10, duration of pain = 7 +/- 4 years). Pain ratings were measured immediately before and 2 minutes and 32 minutes after 25 minutes of cycle ergometry (5 minutes at 50% peak oxygen uptake, then 20 minutes at 70% peak oxygen uptake). We based the pain ratings on subject input on a visual analog scale at 10-second intervals during the 2-minute pressure pain stimulus to the nondominant index finger. Compared with preexercise values, pain ratings were significantly (p < 0.05) decreased after exercise at both 2 and 32 minutes postexercise. We conclude that pressure pain perception can be reduced for more than 30 minutes following aerobic exercise from leg cycling among people with chronic low back pain.

Physiological comparison of walking among bilateral above-knee amputee and able-bodied subjects, and a model to account for the differences in metabolic cost

OBJECTIVE To compare the metabolic cost for prosthetic ambulation among persons with bilateral above-knee amputation with that for able-bodied ambulation, and to test a model that differentiates the metabolic cost of walking into three components. DESIGN Cross-sectional comparison. SETTING Community-dwelling subjects studied at an academic medical center. PARTICIPANTS Five bilateral above-knee amputee subjects with mean (+/-SD) age of 22 +/- 3 years, and five able-bodied control subjects matched for gender, height, weight, and age. INTERVENTION Subjects performed 6-minute bouts of walking at three paced speeds and their chosen walking speed with oxygen uptake being determined during the last 2 minutes of each bout. MAIN OUTCOME MEASURES Chosen walking speed and oxygen uptake during each walking condition. RESULTS The chosen walking speed was 21% slower and induced aerobic demands 49% higher for the amputee subjects. Across specified paced speeds, aerobic demands were 55% to 83% higher for the amputee subjects than for the able-bodied subjects. The described model suggests that the higher metabolic costs for the amputee subjects resulted from greater demands for maintenance of balance and posture and for performing the walking movement. CONCLUSIONS Prosthetic ambulation by young healthy persons with bilateral above-knee amputation induces significantly greater metabolic demands than walking by able-bodied individuals. Although the chosen walking speed of persons with bilateral above-knee amputation is slower, the reduction in speed is insufficient to equalize their metabolic cost with that of able-bodied individuals walking at their chosen walking speed.

Exercisers Achieve Greater Acute Exercise-Induced Mood Enhancement Than Nonexercisers

OBJECTIVE To determine whether a single session of exercise of appropriate intensity and duration for aerobic conditioning has a different acute effect on mood for nonexercisers than regular exercisers. DESIGN Repeated-measures design. SETTING Research laboratory. PARTICIPANTS Adult nonexercisers, moderate exercisers, and ultramarathon runners (8 men, 8 women in each group). INTERVENTIONS Treadmill exercise at self-selected speeds to induce a rating of perceived exertion (RPE) of 13 (somewhat hard) for 20 minutes, preceded and followed by 5 minutes at an RPE of 9 (very light). MAIN OUTCOME MEASURE Profile of Mood States before and 5 minutes after exercise. RESULTS Vigor increased by a mean +/- standard deviation of 8+/-7 points (95% confidence interval [CI], 5-12) among the ultramarathon runners and 5+/-4 points (95% CI, 2-9) among the moderate exercisers, with no improvement among the nonexercisers. Fatigue decreased by 5+/-6 points (95% CI, 2-8) for the ultramarathon runners and 4+/-4 points (95% CI, 1-7) for the moderate exercisers, with no improvement among the nonexercisers. Postexercise total mood disturbance decreased by a mean of 21+/-16 points (95% CI, 12-29) among the ultramarathon runners, 16+/-10 points (95% CI, 7-24) among the moderate exercisers, and 9+/-13 points (95% CI, 1-18) among the nonexercisers. CONCLUSIONS A single session of moderate aerobic exercise improves vigor and decreases fatigue among regular exercisers but causes no change in these scores for nonexercisers. Although total mood disturbance improves postexercise in exercisers and nonexercisers, regular exercisers have approximately twice the effect as nonexercisers. This limited postexercise mood improvement among nonexercisers may be an important deterrent for persistence with an exercise program.

Anthropometric characteristics of ultramarathoners.

Little is known about the anthropometric characteristics of ultramarathon runners. The present work reports on the physical characteristics of the 392 (310 males, 82 females) starters and 270 (216 males, 54 females) finishers of the 2007 Western States Endurance Run, one of the largest 161-km trail runs in North America. Among the starters, mean (and 25th to 75th percentiles) body mass index (BMI) values were 23.2 (21.6 - 24.6) and 20.6 (19.4 - 21.9) kg . m (-2) for the men and women, respectively. Men were significantly taller, heavier and had greater BMIs across all age groups compared with the women. Among the top-5 overall finishers, mean BMI values were 23.2 (range 22.4 - 24.7) for the men and 19.8 (range 17.3 - 21.1) for the women. Average running speed and BMI were negatively correlated for both men (r (2) = 0.11, p < 0.0001) and women (r (2) = 0.10, p = 0.02). From this analysis, it is concluded that those participating in ultramarathon runs can vary widely in physical characteristics with BMI values that would classify some individuals as underweight and others as overweight. BMI varied considerably even among the top finishers, but lower BMI values were associated with faster running times.

Poling forces during roller skiing: effects of technique and speed

PURPOSE Although it has been reported that the majority of propulsive forces are generated through the poles with ski skating, no study has systematically examined poling forces among different skating techniques. The objective of the present study was to examine poling forces and timing during roller skiing on a 2.1% uphill. METHODS Nine highly skilled cross-country skiers roller skied at three paced speeds and maximal speed using the V1 skate (V1), V2-alternate (V2A), V2 skate (V2), and double pole (DP) techniques while poling forces and timing were measured with piezoelectric transducers. RESULTS Peak force (PF) values with the skating techniques were significantly lower than with DP and ranged from 18.9 +/- 3.1% of body weight (BW) to 31.5 +/- 5.6% BW across the speeds of the study. Average force over the entire cycle (ACF) increased with speed with DP, V2A and V1 (P < 0.01) but not with V2. PF and ACF were higher (P < 0.01) with V2 than V1 and V2A. Poling time was longer (P < 0.01) with V2A compared with V1 and V2. CONCLUSIONS The results of this study suggest that 1) the use of the upper body is greater with V2 than with other skating techniques while there is a relatively greater reliance on the lower body for generation of the additional propulsive forces required to increase velocity, and (2) poling forces do not appear to be as effectively applied with V2 as with V2A.