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Six months of calf exercise training in a patient with peripheral arterial disease and intermittent claudication: a case report.

INTRODUCTION

This report describes functional changes in a typical patient with peripheral arterial disease (PAD) and intermittent calf claudication during 26 weeks (6 months) of interval exercise training of the calf muscles. The method of calf training described in this case report is novel. Moreover, the patient was the first subject to complete the protocol as part of a larger randomized controlled trial comparing the efficacy of treadmill walking to calf exercise training for PAD patients with calf claudication.

Lower-extremity PAD affects approximately 20% of older individuals (34). In 2001, the VHA reported 55,916 discharges with peripheral vascular procedures, 54% of whom had PAD (27). Almost all were male and represent 8% of all corresponding U.S. procedures. VA rates for 45-64-year-olds were similar to the general U.S. population for ages 65-74; thus, vascular problems occur earlier and are more severe for veterans.

The etiology of PAD is atherosclerosis in the lower extremities that progresses from stenotic to occluded large and small arteries in the legs (21). Eventually, the leg circulation is unable to adequately perfuse and oxygenate metabolically active leg muscles. The resulting ischemia allows [O.sub.2] demand to exceed [O.sub.2] supply during weight-bearing physical activities. Although not all patients with PAD are symptomatic, the primary symptom of PAD is intermittent claudication in leg muscles during walking. Chronic ischemia promotes oxidative tissue injury, dysfunctional mitochondria, and a decrease in adenosine triphosphate production, thereby compromising bioenergetics in muscles (26).

Consequences of intermittent claudication are decreased physical activity, physical deconditioning, worsening ischemic pain upon walking, and mobility impairment (29,30,32). Furthermore, physical inactivity promotes heart disease, systemic atherosclerosis, and disability (22).

"Vascular rehabilitation" is exercise treatment specifically aimed at improving functional walking abilities in ambulatory patients with PAD. Current clinical guidelines for vascular rehabilitation unanimously recommend walking as the exercise mode of choice (4,8,11,21,34). However, many patients with PAD have conditions that preclude treadmill or surface walking exercise for testing and training, including unstable/severe coronary artery disease, congestive heart failure, hemiparesis, severe arthritis, chronic pain, leg amputation, balance impairment, deconditioning, and other disabling conditions. Gardner et al. (12) reported that, out of 905 veteran PAD patients evaluated for exercise research, 190 (20%) were excluded due to exercise intolerance from factors other than leg pain, e.g., severe CAD, dyspnea, poorly controlled hypertension, cancer, or renal/liver disease. Therefore, substantial numbers of ambulatory PAD patients will not be candidates for treadmill walking training and may benefit from calf exercise training.

Calf exercise has only recently been investigated as an exercise training mode for patients with PAD. Wang et al. (41) trained 14 PAD subjects with individual-leg plantar flexion exercise (4 bouts of 4-minute intervals at 80% of maximal work rate three times per week for eight weeks). Compared to a nontraining control group, the training group significantly increased plantar flexion peak oxygen uptake ([VO.sub.2]peak) and power output by 24% and 44%, respectively, and treadmill [VO.sub.2]peak significantly increased 12.3%. Eleven of 14 patients no longer reported leg pain limitations during treadmill testing at [VO.sub.2]peak. The authors suggested that, since small muscle mass exercise (e.g., calf exercise) increases maximal muscle blood flow and oxygen extraction more than large-muscle-mass exercise (e.g., treadmill), calf exercise training should provide a potent stimulus for vascular adaptation and rehabilitation (24). Figoni et al. (10) used calf exercise training to supplement traditional treadmill and overground walking training in 15 men with PAD and calf claudication. After the 3-month intervention, the improved treadmill test performance was accompanied by greater calf tissue oxyhemoglobin desaturation (deoxygenation) during exercise, suggesting that increased capillarization and diffusion-based enhancement of arteriovenous [O.sub.2] extraction explains the functional improvement.

CASE DESCRIPTION

The patient was a 61-year-old African-American male veteran with diagnosed PAD, Fontaine stage IIa, i.e., able to walk at least 200 m nonstop without an assistive device and free of resting pain or tissue necrosis or amputation resulting from critical ischemia in the lower extremities. After referral to the investigators by a vascular surgeon at the Peripheral Vascular Clinic, the patient was recruited and enrolled in our PAD exercise research project. Prior to physical examination and review of medical history, the prospective research subject signed an informed consent form that was approved by the medical center's institutional review board. He was interviewed, examined, and cleared medically by a physician prior to participation. The physician administered the San Diego Claudication Questionnaire to the patient and classified his PAD as "classic intermittent claudication" (7), which has the following characteristics: (a) claudication occurred in the calf region upon walking, (b) did not begin at standstill or sitting, (c) occurred upon uphill/hurrying or the pain caused the patient to avoid uphill walk/hurrying, (d) if the pain caused uphill/hurrying avoidance, then it occurred at an ordinary walking pace on the level, (e) did not disappear during walk, (f) caused the patient to halt or slow down during walking, and (g) was lessened or relieved within 10 minutes if walking was halted.

For ten years the patient had complained of bilateral intermittent claudication of the calf muscles, with the left being more symptomatic than the right. At present he stated that he could walk only one block before claudication forced him to stop and rest. The patient was a retired postal worker whose primary avocation was visiting local horse racing tracks five days per week. He did not own a car, so he used public transportation (about ten miles) between his residence and the medical center.

Besides symptomatology, the standard diagnostic test for PAD is the "ankle-brachial index" (ABI) which assesses the decrease in arterial pressure supplying the legs in the presence of peripheral arterial stenosis and occlusion; it represents the hemodynamic severity of PAD (31). The ABI was calculated as the ratio of the systolic pressure in the foot (dorsalis pedis artery) or ankle (posterior tibial artery) to the brachial systolic pressure. The more sensitive Doppler ultrasound method was used to detect pulses rather than by simple auscultation. We measured his ankle-brachial indices as 0.55 on the left and 0.95 on the right. Although 0.95 is technically within the normal range of 0.90-1.2, it was noted that the Doppler pulse waveforms of both legs were relatively low amplitude and monophasic instead of biphasic, and therefore abnormal. Previous magnetic resonance arteriography had documented bilateral stenoses in the superficial femoral, profunda femoris, anterior and posterior tibial, peroneal, and popliteal arteries. The patient had several risk factors for PAD: current smoking of 10 cigarettes per day, 55 pack-years smoking history, 30-year history of hypertension, and dyslipidemia. Other comorbidities included stroke (10 years ago) from which he had completely recovered physically, stage III chronic renal insufficiency, and pernicious anemia (hemoglobin concentration = 11.7 gm/dl, hematocrit = 34%).

At the start of training, the patient was 60.8 years of age, 176.5 cm in stature, 54.5 kg in mass, with a body mass index of 17.5 kg x [m.sup.-2]. As part of the screening process for the randomized controlled trial, his maximal walking distance was tested under standardized conditions in a quiet hospital hallway between two orange cones placed on the floor 100 feet (30.48 m) apart. The subject was instructed to walk at a constant, self-selected pace as far as possible before claudication pain forced him to stop and rest. His demonstrated maximal walking distance on a hard smooth surface was 470 m; the primary limiting factor for further walking was claudication pain in the left calf muscles, with less severe pains in his tibialis anterior and hamstring muscles.

ASSESSMENTS

The patient performed several outcome assessment procedures at three time points: before intervention (baseline), after three months of intervention, and after six months of intervention, as follows.

Questionnaires: Four validated questionnaires were administered. The Baltimore Activity Scale for Intermittent Claudication (13) consists of five questions about the effect of claudication on walking, resulting in a score scaled from 0 (least active) to 10 (most active). The International Physical Activity Questionnaire (6) estimates the frequency and duration of vigorous, moderate, and walking activities in the past week and allows computation of the amount of weekly physical activity in MET x min x [week.sup.-1]. The Walking Impairment Questionnaire (33) assesses the effects of claudication on walking distance, speed, and stair-climbing ability, expressed as percentages of the maximal possible score if no impairment exists. The Peripheral Artery Questionnaire (37) measures health-related quality of life of PAD patients. It includes the following seven domains: physical function, symptom stability, symptom frequency/burden, social function, quality of life, treatment satisfaction, and a summary score.

Treadmill exercise test: After a 10-minute supine rest period on a padded treatment table, the patient performed a treadmill exercise test to measure pain-free exercise times (PFET) for each calf and maximal exercise time (MXT). A modified Gardner protocol (16) was employed for a symptom-limited treadmill exercise test. It uses a constant speed of 2 mph and a grade increase of 2% every 2 minutes starting at 022% grade (metabolic equivalent range: 2.5-8.5). The patient was not allowed to support his bodyweight by holding the railings firmly, but only to touch them for balance. For safety, the patient's heart rate and 12-lead ECG waveforms and rhythm were continuously monitored during the test; blood pressures were measured by manual auscultation and recorded before the test, at the end of each 2-minute exercise stage, and during 15 minutes of recovery. We used a 0-4 pain scale (11) for the patient to identify progression of pain during exercise testing and training: 0 = absence of pain, 1 = onset of pain, 2 = moderate pain, 3 = intense pain, 4 = maximal intolerable pain. PFET was determined for each leg in minutes as the time from the start of walking to the onset of calf claudication. MXT was the total walking time in minutes until claudication became intolerable and the patient asked to stop and rest. The treadmill was stopped immediately and the patient resumed the supine resting position on the padded treatment table for 15 minutes. Power output (W) was calculated at the onset of pain in each calf and at maximal tolerable pain (end of treadmill test) as follows: (body mass in kg) x (treadmill speed in m x [min.sup.-1]) x (26.822333 m x [min.sup.-1] per mi x [hr.sup.-1] conversion factor) x sin (arctan grade in % x [100.sup.-1]).

Six-minute walk test: This test measured the patient's maximal walking distance in a 6-minute period, the primary functional walking outcome in this report. Two trials were performed with a 10-minute rest between tests to allow full recovery and disappearance of claudication symptoms. Two orange cones were placed on the floor 100 feet apart in a quiet hospital hallway. The tester instructed the patient to walk as many laps as possible around the cones. The tester followed the patient and provided feedback about elapsed time every minute. The patient completed both trials without stopping to rest. The total distance covered in six minutes was recorded in feet and converted to meters. The typical mean [+ or -] SD 6-minute walk distance in PAD patients is 376 [+ or -] 95 m (14).

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INTERVENTION

After baseline testing was completed, the patient was randomly assigned to the calf training intervention. He began a supervised clinic-based intervention of single-calf interval exercise training with a custom-built calf ergometer that isolates the gastroc-soleus muscle group. Training consisted of 4 bouts per session per leg, 3 sessions per week (usually Monday, Wednesday, and Friday, 7:00-8:45 am), for 26 weeks (from mid-September through mid-March 2009), with the right leg trained before the left leg.

The calf ergometer and its operation are described in detail in a previous publication (9). (See Figure 1.) It was developed at our medical center to provide accurate, reproducible resistance to ankle plantar flexion at specified cadences through a 30[degrees] ankle range of motion from neutral position to 30[degrees] of plantar flexion, paced by an electronic metronome. The exercise consists of alternating concentric and eccentric plantar flexions against the foot pedal that resists with loads from 2 to 20 kg, allowing power outputs to range from approximately 2 W (2 kg load @ 60 bpm) to 30 W (20 kg load @ 90 bpm).

The specific calf exercise training protocol is illustrated in the flowchart in Figure 2. The explicit protocol is necessary for future clinicians and investigators to replicate this case report in order to improve the generalizability of our findings. Because both calves had similar claudication symptoms, they were trained sequentially. The patient began exercise on the calf ergometer at the minimum 2-kg load and 60-bpm cadence, paced by an electronic metronome, with one ankle movement per metronome beat. The patient exercised up to 8 minutes or until pain was rated 4 (intolerable) as judged by him, after which he rested and recovered. As soon as the pain disappeared, the next exercise bout was started. The load and cadence of each exercise bout determined the load and cadence on the subsequent bout. If he exercised 8 minutes on a bout with no claudication pain, the load was increased by 2 kg. If he exercised 8 minutes on a bout with a pain rating of 1 or 2, the cadence of the next bout was increased by 3 bpm. If he exercised 4:00-7:59 on a bout, he performed the next bout at the same load and cadence. If he exercised < 4 minutes on a bout, the load of the next bout was decreased by 3 bpm. This procedure was followed until four bouts were completed for each leg. When the cadence reached 90 bpm, the exercise load was increased by 2 kg and the cadence was lowered to 60 bpm again. Loads of at least 2 kg were always used to allow the calculation of work and power for exercise bout to quantify progress over time. Research staff measured all exercise and rest/recovery times with a hand-held stopwatch and recorded the times, loads, and cadences on log sheets. Pain ratings at the end of each exercise bout were also recorded. The patient performed up to 32 minutes of exercise/session/leg. Each session lasted approximately 1 hour 45 minutes.

For safety purposes, due to the painful nature of this exercise training, patient's blood pressure and heart rate were monitored frequently during training. Specifically, his blood pressure and heart rate were measured by manual auscultation and a digital pulse oximeter before training each leg, during the fourth exercise bout with each leg, and after claudication had subsided to zero after the fourth bout with each leg. These data are not presented here as they will be the subject of another manuscript.

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Work and power output were calculated for each exercise bout, as follows:

x Work in W*min = (exercise time in minutes) x (load in kg) x (cadence in bpm x 60 [bpm.sup.-1])

x Power in W = (work in W x min) x [(exercise time in minutes).sup.-1]

RESULTS

Adherence to the intervention was 100% (78 total sessions in 26 weeks). Pre-, mid-, and posttraining data from questionnaires, 6-minute walk tests, and treadmill exercise tests are presented in Table 1. Table 2 contains the mean [+ or -] SD and changes of the training variables from week 1 and week 26, i.e., beginning and end of the training intervention.

After training, questionnaire-based measures of physical activity increased 133% on the Baltimore Activity Scale for Intermittent Claudication and 276% on the International Physical Activity Questionnaire. The Walking Impairment Questionnaire provided evidence that walking distance improved 389%, speed improved 213%, and stair-climbing improved 23%. The Peripheral Artery Questionnaire data showed large and progressive improvements in physical limitation (301%) and symptom stability (299%). Symptom frequency/burden, quality of life, treatment satisfaction, and the summary score increased by 66-67%, and social function increased by 8%.

Treadmill PFET for the left calf increased 354% during the first three months, and remained relatively steady through six months. After six months of training, treadmill PFET for the right calf increased 248% and pain-free power output increased 501%. Although still limited by left calf claudication, treadmill MXT increased 231% and maximal power output increased by 262%. The mean of two trials of the 6MWT increased 50%, i.e., by 157 m, from 312 to 469 m.

Mean values of work, power, exercise time, rest time, and pain rating for each of four bouts for each leg were averaged for each week and plotted against number of weeks of training to illustrate trends of these variables over time and thus training progress (Figures 3-7). Pain data represent the patient's pain rating at the end of each exercise bout. Recovery times represent the time necessary for the pain rating to decrease to zero.

Average work per exercise bout for each leg increased linearly from week 1 through week 26, by 887% and 803% for left and right calves, respectively (Figure 3). Average power output per exercise bout for each leg increased linearly from week 1 through week 26, by 773% and 809% for left and right calves, respectively (Figure 4). The left calf increased work by an average of 5.1 W*min* per week, and power output increased by an average of 0.6 W per week. The right calf increased work by an average of 5.0 W*min per week, and power output increased by an average of 0.7 W per week. Work and power output for the right calf were usually higher than those for the left calf, especially after week 9.

Mean [+ or -] SD exercise and recovery times per bout remained relatively constant at 7.76 [+ or -] 0.36 minutes and 3.81 [+ or -] 0.38 minutes, respectively for the left calf (Figure 5), and 7.72 [+ or -] 0.20 minutes and 4.11 [+ or -] 0.46 minutes, respectively for the right calf (Figure 6). For both calves, pain ratings (0-4 scale) at the end of exercise bouts averaged 2.8 [+ or -] 0.2 out of 4 (minimum = 1, maximum = 4, mode = 3), with 32% and 11% decreases in reported pain after the training intervention, respectively, for left and right calves (Figure 7). There were no obvious differences in exercise times, recovery times, or pain ratings between left and right legs.

DISCUSSION

The most surprising finding of this case report is the extent of improvement in exercise performance and functional outcomes that can result from exercise training of calf muscle groups. Vascular rehabilitation typically consists of clinic-based treadmill walking exercise training to improve claudication symptoms (11). Treadmill training typically induces 80-180% improvements in grade-incremented treadmill exercise test performance (2), whereas the speed-limited 6-minute walking distance improves only modestly (16%) (12,15). This case study shows that training of small muscles groups such as the gastroc-soleus that limit walking can also improve the same functional outcomes. This finding was not completely unexpected, as training targeted the claudicating muscles that limited walking.

For clarity, the specific functional changes after the training intervention deserve qualification and interpretation. Increased self-reported physical activity scores on the two questionnaires reflect an increase in general lifestyle physical activity, much of which probably involves walking and weight-bearing movements. It is conceivable that this additional lifestyle physical activity contributed to, or confounded, the effects of the clinical exercise intervention. The increased walking distance score means that the patient reported less difficulty walking distances from 20 and 1500 feet. The increased speed score indicates that he perceived less difficulty in traversing one block while walking slowly, walking at an average pace, walking quickly, or running. Similarly, the small improvement in the stair-climbing score indicates that he perceived slightly less difficulty climbing one, two, or three flights of stairs.

Greater posttraining PFET, pain-free power output, MXT, and maximal power output indicate delayed and less severe calf claudication during treadmill walking on steep inclines. A greater 6-minute walk distance indicates increased walking speed within the 6-minute time limit. Taken as a whole, all posttraining changes point toward greater functional walking ability and consequently less functional severity of this patient's PAD. Although exercise training is not known to remove arterial stenoses or occlusions or cure PAD, calf training allowed the patient to function better by alleviating some of the claudication symptoms. After training, his perceived and demonstrated functional performances were still limited by left calf pain, but he was able to perform at higher levels than baseline before his claudication limited him.

Several mechanisms have been proposed to explain how exercise training improves walking function in PAD, including increased leg arterial inflow (17) perhaps due to angiogenesis (growth of new blood vessels in ischemic muscle tissue), changed metabolic properties in exercised muscles (3), improved walking technique and economy (15,35), and increased cardiopulmonary fitness (19), mitochondrial capacity (33), skeletal muscle diffusive capacity (41), calf muscle capillarization (40), and pain tolerance (21). We cannot attribute the improvements in our patient's walking ability to increased cardiopulmonary fitness secondary to calf training, as calf exercise training involves too small a muscle mass to elevate metabolic and cardiopulmonary responses to sufficient levels to induce central cardiopulmonary adaptations (41). The increased general lifestyle physical activity reported by the patient may have induced such changes, but, as we did not measure peak oxygen uptake before and after the intervention, we cannot conclude that the intervention improved peak oxygen uptake and consequently fitness levels. Also, we should not attribute improvements in our patient's walking ability to improved walking technique or economy, as the intervention included neither walking nor walking instruction and practice. It is still possible that the calf exercise training, acting directly on the calf muscles, induced angiogenesis, and increased metabolic activity in ischemic muscles and pain tolerance. This case report did not collect data to suggest the exact mechanisms for improvement.

Walking is still the exercise mode of choice for most ambulatory patients with PAD and claudication. However, calf ergometry is a novel exercise intervention that may be suitable for patients who are less ambulatory, such as patients with severe cardiopulmonary disease, pain of nonvascular origin, or deconditioning. Alternatives to treadmill or over-ground walking may include leg or arm ergometry (39,42), stair-climbing (23), pole-striding (25), and resistance training (20,28), all of which have been shown to improve walking ability. Because less ambulatory patients would probably still have difficulty with these exercise modes, isolated calf exercise training may serve as a preparatory activity for functional walking, as it directly targets the claudicating calf muscles, the limiting factor for ambulation in most patients with classic intermittent claudication. Indeed, Helgerud et al. (18) reported that prior calf exercise training in PAD patients facilitated subsequent treadmill training effects compared to treadmill training alone. Calf exercise also has the advantage of inducing low levels of cardiopulmonary stress, making it more tolerable for patients with severe exercise intolerance secondary to severe deconditioning or cardiopulmonary disease. Consequently, it also has the disadvantage of lacking potential for direct central cardiopulmonary training effects.

General calf exercise can be performed on existing weight training equipment such as the leg press and seated calf exercise machines, as well as seated heel raises with a weight placed on the thighs and standing heel raises with full or partial bodyweight-bearing. However, tight controls over many ergometric parameters (such as isolation of the gastroc-soleus muscle group, range of motion, and force requirements necessary for work and power calculations) are lacking. An isokinetic dynamometer (e.g., KinCom, Biodex, Cybex, Lido, BTE, etc.) can also be used, but the instrumentation is expensive, large, and nonportable, and is impractical for use with training groups of patients. Hence, if calf exercise training is shown to be clinically valuable in larger patients groups, it is possible to develop our research instrument into a practical clinical device for clinical calf exercise testing and training. Indeed, ergometers could be developed for other specific claudicating muscle groups such as tibialis anterior, quadriceps, hamstrings, or gluteals.

This paper illustrates how weekly work and power data can be used to track progress at frequent intervals during vascular rehabilitation. To our knowledge, this is the first report of the use of such data in a patient with PAD. Due to time and resource constraints, it is unlikely that treadmill exercise tests with direct medical supervision can be repeated on a weekly basis in rehabilitation settings. However, each bout of either calf exercise, or exercise on any ergometer, can yield work and power output data to document daily or weekly improvements in exercise capacity that may parallel functional improvements. For over 30 years, similar data have been used to develop system models of training for athletic performance and to understand the relationship between the training stimulus and induced physiological and functional training responses (1).

Although this paper reports dramatic improvements in both ergometric exercise performance and walking function, it is not definitive evidence of efficacy of calf exercise training for the PAD population. For this evidence, it would require the results of a randomized controlled trial that ideally reveals a dose-response relationship between ergometric exercise performance and functional improvements at frequent intervals.

The standardized protocol in Figure 2 placed several constraints on several training parameters, including the 8-minute interval time limit, four exercise bouts per session, how specific exercise times triggered changes of cadence and load on subsequent bouts, and rest periods being limited to the time required for pain to dissipate before starting the next bout. The 8-minute bout interval time limit was set so most exercise bouts would to be similar to the 6-minute walk time, the primary functional outcome of this case report and larger research project. Each bout tends to produce a maximal effort and the protocol increments cadence and load as the patient is capable of performing more work at higher power outputs. These constraints are likely responsible for the consequent rates of "overload" that are necessary for progression of training for each leg over time. The protocol produced linear increases in training work and power output over the 26-week period. This protocol was acceptable to the patient. Whether or not this protocol is optimal for producing maximal rates and ultimate amounts of improvement for this or other PAD patients remains to be seen.

CONCLUSIONS

In a typical patient with PAD and classic intermittent calf claudication, exercise training of bilateral calf muscle groups improved functional outcomes on questionnaire-based tests and on both treadmill and over-ground walking tests. The standardized protocol produced linear increases in training work and power output over a 26-week period. Work and power data suggest that exercise and functional improvements would continue beyond 26 weeks of training.

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AUTHOR CORRESPONDENCE:

Stephen F. Figoni, PhD, RKT

PM&RS (117), VAWLAHC

11301 Wilshire Blvd.

Los Angeles, CA 90073

Phone: (562) 881-2151

FAX: (310) 268-4935

E-mail: stephen.figoni@va.gov

Reprints will not be available from the author.

Stephen F. Figoni, PhD, RKT [1], Charles F. Kunkel, MD, MS [1,3], A. M. Erika Scremin, MD [1,3], Howard Dedes, MD [2], Gus Kalioundji, MD [2], Bahnam Thomas, DO [2], Huy T. Bang, BS [1], Peony Liu, BA, BS [3]

[1] VA Greater West Los Angeles Healthcare System (GLA), West Los Angeles Healthcare Center, Los Angeles, CA. [2] UCLA/VA GLA PM&R Residency Program, Los Angeles, CA. [3] Division of Physical Medicine and Rehabilitation, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, CA.
Table 1. Outcome data at baseline and after 13 and 26 weeks of
training. Absolute and relative changes from baseline to 26 weeks
are also shown.

                                      Baseline   13 weeks   26 weeks

                                              QUESTIONNAIRES

Baltimore Activity Scale for             3          7          7
Intermittent Claudication (0-10)
International Physical Activity         1386       3208       5214
Questionnaire (MET.min/wk)
Walking Impairment (distance, % max)    15.2       51.2       74.3
Walking Impairment (speed, % max)       25.0       73.9       78.3
Walking Impairment (stairs, % max)      54.2       54.2       66.7
Peripheral Artery Questionnaire:
    Physical limitation                 13.3       20.0       63.3
    Symptom stability                   16.7       50.0       66.7
    Symptom frequency/burden            31.6       31.6       52.6
    Social function                     72.2       77.8       77.8
    Quality of life                     40.0       53.3       66.7
    Treatment satisfaction              40.0       53.3       66.7
    Summary                            157.1      177.4      260.4

                                            6-MINUTE WALK TESTS

Distance (m)--Trial 1                  311.7      426.7      451.1
Distance (m)--Trial 2                  312.1      479.8      487.7
Distance (m)--Mean of Trials 1 & 2     311.9      453.2      469.4

                                              TREADMILL TESTS

Left  Pain-free exercise time (min)     2.00       9.08       8.50
      Pain-free power output (W)         0 *      239.9      233.9
Right Pain-free exercise time (min)     3.88       9.58      13.50
      Pain-free power output (W)        58.1      239.9      349.5
Maximal exercise time (min)             7.25      18.00      24.00
Maximal power output (W)               174.1      417.1      630.3

                                      [delta]    % [delta]

                                        QUESTIONNAIRES

Baltimore Activity Scale for             4         133
Intermittent Claudication (0-10)
International Physical Activity         3828       276
Questionnaire (MET*min/wk)
Walking Impairment (distance, % max)    59.1       389
Walking Impairment (speed, % max)       53.3       213
Walking Impairment (stairs, % max)      12.5        23
Peripheral Artery Questionnaire:
    Physical limitation                 40.0       301
    Symptom stability                   50.0       299
    Symptom frequency/burden            21.0        66
    Social function                     5.6         8
    Quality of life                     26.7        67
    Treatment satisfaction              26.7        67
    Summary                            103.3        66

                                       6-MINUTE WALK TESTS

Distance (m)--Trial 1                  139.4        48
Distance (m)--Trial 2                  175.6        56
Distance (m)--Mean of Trials 1 & 2     157.5        50

                                       TREADMILL TESTS

Left Pain-free exercise time (min)      6.50       325
     Pain-free power output (W)        233.9        *

Right Pain-free exercise time (min)     9.62       248
      Pain-free power output (W)       291.4       501
Maximal exercise time (min)            16.75       231
Maximal power output (W)               456.2       262

* No external work against gravity is performed when treadmill grade
is 0%; therefore, % change from 0 W is undefined.

Table 2. Training variables at baseline and after 13 and 26 weeks of
training. Absolute and relative changes from baseline to 26 weeks and
mean change per week are also shown. Data for weeks 1 and 26 are mean
[+ or -] SD of all exercise or recovery bouts within the week (4 bouts
per session x 3 sessions per week = 12 bouts per week).

                                    Week 1               Week 26

LEFT
Work (W x [min.sup.-1])       14.8 [+ or -] 3.3    146.7 [+ or -]6.2
Power (W)                      2.2 [+ or -] 0.0     18.3 [+ or -] 0.8
Maximal exercise time (min)   6.75 [+ or -] 1.51    8.00 [+ or -] 0.00
Recovery time/bout (min)      3.46 [+ or -] 0.70    3.93 [+ or -] 1.24
Pain rating (0-4)              3.7 [+ or -] 0.5      2.5 [+ or -] 0.5

RIGHT
Work (W x [min.sup.-1])       16.3 [+ or -] 2.0    146.9 [+ or -] 25.7
Power (W)                      2.2 [+ or -] 0.0     20.0 [+ or -] 0.0
Maximal exercise time (min)   7.40 [+ or -] 0.89    7.34 [+ or -] 1.28
Recovery time (min)           3.37 [+ or -] 0.99    4.00 [+ or -]1.66
Pain rating (0-4)              3.5 [+ or -] 0.5      3.1 [+ or -]0.7

                               [delta]     % [delta]   Mean [delta]/wk

LEFT
Work (W x [min.sup.-1])          131.8         887         5.1
Power (W)                         16.1         773         0.6
Maximal exercise time (min)       1.25          18        0.05
Recovery time/bout (min)          0.47          14        0.02
Pain rating (0-4)                 -1.2         -32        -0.0

RIGHT
Work (W x [min.sup.-1])          130.6         803         5.0
Power (W)                         17.8         809         0.7
Maximal exercise time (min)      -0.05           1        0.00
Recovery time (min)               0.63          19        0.02
Pain rating (0-4)                 -0.4         -11        -0.0
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Article Details
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Title Annotation:Clinical Applications
Author:Figoni, Stephen F.; Kunkel, Charles F.; Scremin, A.M. Erika; Dedes, Howard; Kalioundji, Gus; Thomas,
Publication:Clinical Kinesiology: Journal of the American Kinesiotherapy Association
Article Type:Case study
Geographic Code:1USA
Date:Sep 22, 2009
Words:6813
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