Difference of Knee Strength Recovery Between Revision and Primary ACL Reconstruction.

Different grafting procedures are available to restore knee stability after revision anterior cruciate ligament (ACL) reconstruction. We compared knee strength recovery between ACL revision surgery and primary reconstruction. One hundred and ten patients with ACL revision surgery were matched with 110 patients with primary reconstruction based on the graft procedure. The isokinetic knee strength had been assessed for the first 9 months post-surgery. Knee laxity, function, and activity score were also evaluated. Limb symmetry index for knee extensor and flexor strength was not different at 4-, 6- and 9-months post-surgery between revision surgery and primary reconstruction. These results depended on ipsilateral or contralateral graft choice. Ipsilateral hamstring tendon (HT) and contralateral bone-patellar-tendon-bone (BPTB) graft procedures were similar for a revision of a BPTB graft failure. Contralateral HT procedure was better than ipsilateral BPTB procedure for a revision of a HT graft failure. The early recovery of isokinetic knee strength after ACL revision surgery regardless of the HT or BPTB procedures, was similar to the recovery after primary ACL reconstruction with the same graft technique. These results apparently depended on a temporary quadriceps arthrogenic muscle inhibition and on a persistent donor site morbidity, concerning the new and the previous grafts, respectively.

Impact of Prescribed Exercise on the Physical and Cognitive Health of Adults with Down Syndrome: The MinDSets Study.

The duplication of chromosome 21, as evidenced in Down Syndrome (DS), has been linked to contraindications to health, such as chronotropic and respiratory incompetence, neuromuscular conditions, and impaired cognitive functioning. The purpose of this study was to examine the effects of eight weeks of prescribed exercise and/or cognitive training on the physical and cognitive health of adults with DS. Eighty-three participants (age 27.1 ± 8.0 years) across five continents participated. Physical fitness was assessed using a modified version of the six-minute walk test (6MWT), while cognitive and executive functions were assessed using the Corsi block test, the Sustained-Attention-To-Response Task (SART), and the Stroop task (STROOP). All were completed pre- and post-intervention. Participants were assigned to eight weeks of either exercise (EXE), 3 × 30 min of walking/jogging per week, cognitive training (COG) 6 × ~20 min per week, a combined group (COM), and a control group (CON) engaging in no intervention. 6MWT distance increased by 11.4% for EXE and 9.9% for COM (p < 0.05). For SART, there were positive significant interactions between the number of correct and incorrect responses from pre- to post-intervention when participants were asked to refrain from a response (NO-GO-trials) across all experimental groups (p < 0.05). There were positive significant interactions in the number of correct, incorrect, and timeout incompatible responses for STROOP in EXE, COG, and COM (p < 0.05). Walking generated a cognitive load attributed to heightened levels of vigilance and decision-making, suggesting that exercise should be adopted within the DS community to promote physical and cognitive well-being.

The effects of lower limb ischaemic preconditioning: a systematic review.

Ischaemic preconditioning (IPC) involves the use of repeated occlusions and reperfusions of the peripheral muscle blood supply at a limb. This systematic literature review examines the typical responses in response to the method of application during an IPC applied at the lower limb. This review focuses on the physiological responses for VO2max, haemoglobin, metabolic and genetic responses to various IPC interventions. The literature search was performed using four databases and assessed using the PRISMA search strategy and COSMIN to assess the quality of the articles. Seventeen articles were included in the review, with a total of 237 participants. While there is variation in the method of application, the average occlusion pressure was 222 ± 34 mmHg, ranging from 170 to 300 mmHg typically for 3 or 4 occlusion cycles. The distribution of this pressure is influenced by cuff width, although 8 studies failed to report cuff width. The majority of studies applies IPC at the proximal thigh with 16/17 studies applying an occlusion below this location. The results highlighted the disparities and conflicting findings in response to various IPC methods. While there is some agreement in certain aspects of the IPC manoeuvre such as the location of the occlusion during lower limb IPC, there is a lack of consensus in the optimal protocol to elicit the desired responses. This offers the opportunity for future research to refine the protocols, associated responses, and mechanisms responsible for these changes during the application of IPC.

Intra- and Inter-Day Reliability of the NIRS Portamon Device after Three Induced Muscle Ischemias.

(1) Background: Near-infrared spectroscopy (NIRS) is an innovative and non-invasive technology used to investigate muscular oxygenation. The aim of this study is to assess the within- and between-session reliability of the NIRS Portamon (Artinis, Elst, Netherlands) device following three sets of induced muscle ischemia. (2) Methods: Depending on the experimental group (G1, G2 or G3), a cuff was inflated three times on the left upper arm to 50 mmHg (G1), systolic blood pressure (SBP) + 50 mmHg (G2) or 250 mmHg (G3). Maximum, minimum and reoxygenation rate values were assessed after each occlusion phase, using a Portamon device placed on the left brachioradialis. Reliability was assessed with intraclass correlation coefficient (ICC) value and ICC 95% confidence interval (CI-95%), coefficient of variation (CV) and standard error of measurement (SEM) (3) Results: Our results showed a good to excellent reliability for maximums and minimums within-session. However, the reoxygenation rate within sessions as well as measurements between sessions cannot predominantly show good reliability. (4) Conclusions: Multiple measurements of maximums and minimums within a single session appeared to be reliable which shows that only one measurement is necessary to assess these parameters. However, it is necessary to be cautious with a comparison of maximum, minimum and reoxygenation rate values between sessions.

Relevant Strength Parameters to Allow Return to Running after Primary Anterior Cruciate Ligament Reconstruction with Hamstring Tendon Autograft.

After anterior cruciate ligament reconstruction (ACLR), a progressive process is followed from rehabilitation to the return to sport including a crucial step known as the return to running. Return to running (RTR) can be predicted by an isokinetic knee strength assessment at 4 months post-surgery. All patients who had primarily undergone ACLR with a hamstring autograft procedure between 2010 and 2020 were included in this study. Four months after surgery, patients were evaluated using an isokinetic knee strength test. Patients were monitored until the 6th month post-surgery to see if they had returned to running. Comparisons were carried out between the two groups-the RTR and the no-RTR. A multivariate logistic regression analysis was used to predict the RTR status from explicative parameters. Receiver Operating Characteristic (ROC) curves were established to identify cutoffs with their characteristics. A total of 413 patients were included and 63.2% returned to running at 4 months post-surgery. The mean Lysholm score, knee complication rate, and isokinetic parameters were statistically different between both groups. Using a multivariate logistic regression model and ROC curves, the best isokinetic parameter to assist with the decision to allow an RTR was the quadriceps limb symmetry index at 60°/s with a cutoff of 65%. The hamstring LSI at 180°/s could be added (cutoff of 80%) to slightly increase the prediction of an RTR. Quadriceps strength normalized to body weight at 60°/s is a useful parameter (cutoff: 1.60 Nm/kg) but measurements on both sides are necessary. Isokinetic parameters are objective parameters to allow a return to running at 4 months after ACLR with a hamstring procedure.

Consequences of Patellar Tendinopathy on Isokinetic Knee Strength and Jumps in Professional Volleyball Players.

Patellar tendinopathy (PT) in professional volleyball players can have an impact on their careers. We evaluated the impact of this pathology in this specific population in terms of isokinetic strength and jumping performances. Thirty-six professional male volleyball players (mean age: 24.8 ± 5.2) performed isokinetic knee assessments, single-leg countermovement jumps and one leg hop test. They filled out the Victorian Institute of Sport Assessment-Patella (VISA-P) score. Two groups were assessed: "PT group" (n = 15) and "control group" (n = 21). The VISA-P score was lower in the PT group (p < 0.0001). No difference was found between the isokinetic strength limb symmetry index and the jump performance limb symmetry index. The healthy legs of the control group were compared with the affected (PT+) and the unaffected legs (PT−) of the PT group. Compared with the healthy legs, both PT+ and PT− legs showed decreased values of quadriceps and hamstring strengths. Only PT+ legs scored lower than healthy legs in countermovement jumps and hop tests. No differences were found between PT+ and PT− legs for muscle strengths and jumps. A low correlation existed between quadriceps strength and jumping performances (r > 0.3; p < 0.001). Volleyball players with PT showed a decrease in the isokinetic knee strength. This strength deficit was found both on the symptomatic legs and the asymptomatic ones. Jumps were only significantly altered on the pathological legs. Highlighting that the unaffected limbs were also impaired in addition to the affected limbs may help provide a better adaptation of the rehabilitation management.

Quantifying the effects of four weeks of low-volume high-intensity sprint interval training on V̇O2max through assessment of hemodynamics.

BACKGROUND: Sprint interval training is a popular workout modality. Studies have eluded to a positive effect on maximal oxygen uptake, however little is known about the mechanistic basis of this adaptation. Therefore, the purpose of this study was to determine the effects of a short-term high-intensity sprint interval training (SIT) intervention on V̇O2max through quantification of both the respiratory and hemodynamic responses. METHODS: Thirty-six physically active participants undertook 4 weeks of either cycling-based SIT (8×20 s at 170% P-V̇O2max with 10 s recovery) or continuous exercise training (CET) (30 min at 70% P-V̇O2max) 3 times per week. V̇O2max, blood-based markers and hemodynamic responses were assessed pre and post the intervention period. V̇O2max was assessed using breath-by-breath open circuit spirometry, while hemodynamic responses were monitored using thoracic impedance cardiography. RESULTS: V̇O2max exhibited a non-significant 4.1% increase (ES=0.24) for SIT with 7.0% P=0.007 (ES=0.40) increase for CET. Hemodynamic responses (maximal cardiac output, maximal stroke volume) displayed non-significant responses for CET and SIT while a-vO2dif-max increased from 15.8±4.8 to 18.3±2.9 mL/100 mL) (P=0.02) (ES=0.63) in SIT. CONCLUSIONS: V̇O2max is a function of maximal cardiac output and a-vO2dif-max, so for a meaningful change to occur in cardiorespiratory fitness, there must be a concomitant increase in O2 delivery. This study demonstrates that a low volume SIT intervention evokes peripherally mediated responses (a-vO2dif) and anaerobic substrate utilization rather than O2 delivery components. Future works should address the time course of the responses and when assessing V̇O2max-based responses that due attention be given to the hemodynamic responses as means of quantification of the response.

Real-life adaptations in walking patterns in patients with established peripheral arterial disease assessed using a global positioning system in the community: a cohort study.

OBJECTIVE: Lower extremity peripheral arterial disease (PAD) is a chronic condition most commonly presenting with intermittent claudication (IC). Intermittent claudication limits walking ability and may negatively affect health-related quality of life. Treadmill assessment of maximal walking distance (MWD) is the gold standard to assess PAD symptom severity. Despite being a well-established and reproducible tool, it may be inappropriate (due to frailty or fear) for some patients and only describes maximal abilities for a single walk test. Global positioning systems (GPS) have been proposed as reliable and reproducible tool to measure total, mean and maximal walking distances in patients with PAD, in the community setting. Using GPS, our study attempted to explore what happens to the walking ability of patients with IC following no intervention under 'real-life' conditions. DESIGN AND METHODS: Using the GlobalSat DG100 GPS, forty-three patients (69 ± 9 years; nine female; no invasive interventions or rehabilitation) undertook two 60-min walking assessments, 6 months apart. Assessments took place in community spaces that had even terrain, no tall trees or buildings and were free from motorized vehicles. Global positioning systems-measured maximum walking distance was the main study outcome measure. RESULTS: Over the 6-month period, patients demonstrated significantly shorter GPS-measured, mean (552 m versus 334 m; P = 0·02) and maximum (714 m versus 545 m; P = 0·04) walking distances, stopping also more frequently (nine versus five times; P = 0·03). CONCLUSIONS: Given the reported symptom progression, we advocate early intervention (e.g. exercise interventions) combined with frequent patient monitoring in attempts to maintain or improve walking ability.

The Effects of Non-Contingent Feedback on the Incidence of Plateau at V̇O2max.

The purpose of this study was to examine the effects of non-contingent feedback in the form of heart rate (HR) on the incidence of plateau at V̇O2max. Ten physically active males (age 24.8 yrs ± 4.2; mass 81.4 ± 9.0 kg; stature 1.80 ± 0.11 m, V̇O2max 53.2 ± 5.8 ml·kg-1.min-1) who were V̇O2max testing naïve but were cognisant as to the heart rate responses to exercise completed four incremental tests to volitional exhaustion, separated by ~72 h for the determination of V̇O2max and gas exchange threshold. The first trial served as a familiarisation with the remaining three being experimental conditions where HR was presented in a screen projection as either the actual response (HR-A) or 10 b·min-1 higher than recorded (HR-H) or 10 b·min-1 lower (HR-L). Throughout all trials V̇O2 was recorded on a breath-by-breath basis with plateau criteria of ≤ 50 ml·min-1. RESULTS: A significant difference was observed for Δ V̇O2 over the final two consecutive 30s sampling periods between HR-A, both HR-L and HR-H (p = 0.049) and for the incidence of plateau response between condition (p = 0.021). An additional significant difference was observed for sub-maximal Δ V̇O2 responses between HR-A and HR-H (p = 0.049) and HR-A and HR-L (p = 0.006). Non-significant differences were observed for all other criteria. These data indicate that when presented with non-contingent feedback in the form of HR, that the perceptually orientated pacing schema becomes disrupted promoting a sparing of the finite anaerobic capacity to compensate for the imbalance between the afferent signal and perception of effort.

Accuracy of a low-cost global positioning system receiver for estimating grade during outdoor walking.

The aim of this study was to assess, for the first time, the accuracy of a low-cost global positioning system (GPS) receiver for estimating grade during outdoor walking. Thirty subjects completed outdoor walks (2.0, 3.5 and 5.0 km · h-1) in three randomized conditions: 1/level walking on a 0.0% grade; 2/graded (uphill and downhill) walking on a 3.4% grade; and 3/on a 10.4% grade. Subjects were equipped with a GPS receiver (DG100, GlobalSat Technology Corp., Taiwan; ~US$75). The GPS receiver was set to record at 1 Hz and its antenna was placed on the right shoulder. Grade was calculated from GPS speed and altitude data (grade = altitude variation/travelled distance × 100). Two methods were used for the grade calculation: one using uncorrected altitude data given by the GPS receiver and another one using corrected altitude data obtained using map projection software (CartoExploreur, version 3.11.0, build 2.6.6.22, Bayo Ltd, Appoigny, France, ~US$35). Linear regression of GPS-estimated versus actual grade with R 2 coefficients, bias with 95% limits of agreement (±95% LoA), and typical error of the estimate with 95% confidence interval (TEE (95% CI)) were computed to assess the accuracy of the GPS receiver. 444 walking periods were performed. Using uncorrected altitude data, we obtained: R 2 = 0.88 (p < 0.001), bias = 0.0 ± 6.6%, TEE between 1.9 (1.7-2.2)% and 4.2 (3.6-4.9)% according to the grade level. Using corrected altitude data, we obtained: R 2 = 0.98 (p < 0.001), bias = 0.2 ± 1.9%, TEE between 0.2 (0.2-0.3)% and 1.0 (0.9-1.2)% according to the grade level. The low-cost GPS receiver used was weakly accurate for estimating grade during outdoor walking when using uncorrected altitude data. However, the accuracy was greatly improved when using corrected altitude data. This study supports the potential interest of using GPS for estimating energy expenditure during outdoor walking.

Predicting metabolic rate during level and uphill outdoor walking using a low-cost GPS receiver.

The objective of this study was to assess the accuracy of using speed and grade data obtained from a low-cost global positioning system (GPS) receiver to estimate metabolic rate (MR) during level and uphill outdoor walking. Thirty young, healthy adults performed randomized outdoor walking for 6-min periods at 2.0, 3.5, and 5.0 km/h and on three different grades: 1) level walking, 2) uphill walking on a 3.7% mean grade, and 3) uphill walking on a 10.8% mean grade. The reference MR [metabolic equivalents (METs) and oxygen uptake (V̇o2)] values were obtained using a portable metabolic system. The speed and grade were obtained using a low-cost GPS receiver (1-Hz recording). The GPS grade (Δ altitude/distance walked) was calculated using both uncorrected GPS altitude data and GPS altitude data corrected with map projection software. The accuracy of predictions using reference speed and grade (actual[SPEED/GRADE]) data was high [R(2) = 0.85, root-mean-square error (RMSE) = 0.68 MET]. The accuracy decreased when GPS speed and uncorrected grade (GPS[UNCORRECTED]) data were used, although it remained substantial (R(2) = 0.66, RMSE = 1.00 MET). The accuracy was greatly improved when the GPS speed and corrected grade (GPS[CORRECTED]) data were used (R(2) = 0.82, RMSE = 0.79 MET). Published predictive equations for walking MR were also cross-validated using actual or GPS speed and grade data when appropriate. The prediction accuracy was very close when either actual[SPEED/GRADE] values or GPS[CORRECTED] values (for level and uphill combined) or GPS speed values (for level walking only) were used. These results offer promising research and clinical applications related to the assessment of energy expenditure during free-living walking.

Global positioning system use in the community to evaluate improvements in walking after revascularization: a prospective multicenter study with 6-month follow-up in patients with peripheral arterial disease.

UNLABELLED: Revascularization aims at improving walking ability in patients with arterial claudication. The highest measured distance between 2 stops (highest-MDCW), the average walking speed (average-WSCW), and the average stop duration (average-DSCW) can be measured by global positioning system, but their evolution after revascularization is unknown.We included 251 peripheral artery diseased patients with self-reported limiting claudication. The patients performed a 1-hour stroll, recorded by a global positioning system receiver. Patients (n = 172) with confirmed limitation (highest-MDCW <2000m) at inclusion were reevaluated after 6 months. Patients revascularized during the follow-up period were compared with reference patients (ie, with unchanged lifestyle medical or surgical status). Other patients (lost to follow-up or treatment change) were excluded (n = 89).We studied 44 revascularized and 39 reference patients. Changes in highest-MDCW (+442 vs. +13 m) and average-WSCW (+0.3 vs. -0.2 km h) were greater in revascularized than in reference patients (both P < 0.01). In contrast, no significant difference in average-DSCW changes was found between the groups. Among the revascularized patients, 13 (29.5%) had a change in average-WSCW, but not in highest-MDCW, greater than the mean + 1 standard deviation of the change observed for reference patients.Revascularization may improve highest-MDCW and/or average-WSCW. This first report of changes in community walking ability in revascularized patients suggests that, beyond measuring walking distances, average-WSCW measurement is essential to monitor these changes. Applicability to other surgical populations remains to be evaluated. REGISTRATION: http://www.clinicaltrials.gov/ct2/show/NCT01141361.

Prior Knowledge of Trial Number Influences the Incidence of Plateau at VO2max.

UNLABELLED: The purpose of this study was to assess the VO2max plateau response at VO2max during a series of pre-determined trials. METHODS: Ten male well-trained athletes (age, 23.0 ± 3.2; height, 183.3 ± 5.5 cm; mass 77.5 ± 11.1 Kg; VO2max 66.5 ± 5.0 ml(.)kg(-1,)min(-1)), but who were VO2max testing naïve and with prior-knowledge of trial number completed four incremental tests to volitional exhaustion, separated by ~72-h for the determination of VO2max and gas exchange threshold. Throughout all trials VO2max was recorded on a breath-by-breath basis using a pre-calibrated metabolic cart, using a plateau criterion of Δ VO2 ≤1.5 ml(.)kg(-1.)min(-1) over the final 2 consecutive 30 s sampling periods. A significant difference was observed between trial-1 and trial-4 for plateau incidence (p = 0.0285) rising from 20% in trial-1 to a 70% response rate in trial-4. Furthermore a significant difference was observed for VO2dif (difference between criterion value and Δ VO2) in trial-1, 1.02 ± 1.69 ml(.)kg(-1.)min(-1) (p = 0.038), with non-significant differences observed for all other trials, despite a non-significant difference for VO2max across all trials (p > 0.05). Finally, a significant difference was observed for effort perception (RPE) at volitional exhaustion between trial-1 (17.7 ± 1.3) and trial-4 (19.0 ± 1.4) (p = 0.0052). These data indicate that prior-knowledge of trial number can influence the manifestation of the VO2 plateau in a group of well-trained male athletes, thereby suggesting that a form of effort control is established in order to preserve the finite anaerobic capacity. Key pointsIn well-trained athletes the incidence of plateau at VO2max increases in conjunction with an increase in trial number and the associated sensations of pain and fatigue.By informing the participant of the number of trials to be completed a closed-loop condition is developed whereby effort in all trials is compared to a perceptually developed template.Closed-loop condition leads to a sparing of the finite anaerobic capacity during incremental tests when the number of trials to be completed is known.

Applicability of global positioning system for the assessment of walking ability in patients with arterial claudication.

OBJECTIVE: This study determined for the first time the clinical applicability of a global positioning system (GPS)-monitored community-based walking ability assessment in a large cohort of patients with peripheral artery disease (PAD). METHODS: A multicenter study was conducted among PAD patients who complained of intermittent claudication. Patients equipped with a GPS device performed a community-based outdoor walk. We determined the number of technically satisfactory GPS recordings (attempt No. 1). Patients with unsatisfactory GPS recordings were asked to perform a second attempt (attempt No. 2). From the satisfactory recordings obtained after attempts No. 1 and No. 2, we analyzed several GPS parameters to provide clinical information on the patients' walking ability. Results are reported as median (interquartile range). RESULTS: A total of 218 patients performed an outdoor walk. GPS recordings were technically satisfactory in 185 patients (85%) and in 203 (93%) after attempts No. 1 and No. 2, respectively. The highest measured distance between two stops during community walking was 678 m (IQR, 381-1333 m), whereas self-reported maximal walking distance was 250 m (IQR, 150-400 m; P < .001). Walking speed was 3.6 km/h (IQR, 3.1-3.9 km/h), with few variations during the walk. Among the patients who had to stop during the walk, the stop durations were <10 minutes in all but one individual. CONCLUSIONS: GPS is applicable for the nonsupervised multicenter recording of walking ability in the community. In the future, it may facilitate objective community-based assessment of walking ability, allow for the adequate monitoring of home-based walking programs, and for the study of new dimensions of walking in PAD patients with intermittent claudication.

Influence of blood donation on the incidence of plateau at VO2max.

PURPOSE: The purpose of this study was to examine the effects of reductions in blood volume and associated oxygen-carrying capacity on the incidence of plateau at VO2max. METHODS: Fifteen well-trained athletes (age 23.3 ± 4.5; mass 77.4 ± 13.1 kg, height 180.1 ± 6.0 cm) completed three incremental cycle tests to volitional exhaustion, of which the first was defined as familiarisation, with the remaining two trials forming the experimental conditions of pre- (UBL) and post-(BLE) blood donation (~ 450 cm(3)). The work rate for the incremental tests commenced at 100 W for 60 s followed by a ramp of 0.42 W s(-1), with cadence being held constant at 80 rpm. Throughout all trials, VO2 was determined on a breath-by-breath basis using a pre-calibrated metabolic cart. The criteria for plateau determination was a ∆VO2 ≤ 50 ml min(-1) over the final two consecutive 30 s sampling periods. RESULTS: Despite a significant (P = 0.0028) 9.4 % reduction in haemoglobin concentration and 10.8 % (P = 0.016) reduction in erythrocyte count between UBL and BLE, there was no change in plateau incidence. However, significant differences were observed for both VO2max (P = 0.0059) 51.3 ± 7.6 (UBL) 48.4 ± 7.9 ml kg(-1) min(-1) (BLE) and gas exchange threshold arrival time 383.4 ± 85.2 s (UBL) 349.2 ± 71.4 s (BLE) (P = 0.0028). CONCLUSION: These data suggest that plateau at VO2max is unaffected by O2 availability lending support to the notion of the plateau being dependent on the anaerobic capacity and the classically orientated concept of VO2max.

Feasibility and validity of self-reported walking capacity in patients with intermittent claudication.

OBJECTIVE: The primary aim of this study was to assess if self-reported measures of walking limitation correlate better with a community-based assessment of maximum walking distance (MWD) than they do with laboratory-based tests in patients with intermittent claudication. A secondary aim was to examine the effect of prior objective testing on these correlations. METHODS: Thirty-one patients completed three self-report tools (self-reported MWD; Walking Impairment Questionnaire [WIQ]; Estimation of Ambulatory Capacity by History-Questionnaire [EACH-Q]) immediately before and approximately 1 week after a series of objective tests (incremental treadmill walking test, 6-minute walk test, 1-hour global positioning system [GPS] recording of a community walk). We analyzed the feasibility of the self-report tools in terms of number of errors and their correlation (r) with objective measures. RESULTS: The correlations of self-report tests to GPS-MWD (range, .579-.808) were consistently higher than with the treadmill test (range, .310-.584) and 6-minute walk test (range, .414-.613). The WIQ had the highest proportion of errors, both at first and second completion (58% and 42%, respectively), compared with self-reported MWD (23% and 13%, respectively) and the EACH-Q (6.5% and 13%, respectively). Correlations were improved with the second set of self-report tests (range, .310-.595 to .414-.808). CONCLUSIONS: The fact that all self-report tools correlated better with a community-based measure of MWD using GPS than with laboratory results confirms that they measure what they aim to: community-based MWD. In addition, prescription of a community walk might help patients to better estimate their walking limitation.

Proximal ischemia is a frequent cause of exercise-induced pain in patients with a normal ankle to brachial index at rest.

BACKGROUND: Excluding a vascular origin of exercise-related pain is often difficult in clinical practice. Recent papers have underlined the frequent association of concurrent lumbar spine degenerative disease and peripheral arterial disease. Furthermore, even when suspected, isolated exercise-induced proximal ischemia is difficult to diagnose. Measurement of transcutaneous oxygen pressure (tcpO2) is an interesting and accurate method to differentiate proximal (buttock) from distal (calf) regional blood flow impairment (RBFI) during exercise. OBJECTIVES: We searched for isolated proximal-without-distal RBFI as a possible cause of claudication, in patients with borderline (ABI-b: 0.91 - 0.99) or normal (ABI-n: 1.00 to 1.40) ankle to brachial index at rest. STUDY DESIGN: Retrospective cohort design study. We analyzed patients referred to our laboratory with symptom limiting claudication and an ankle brachial index within normal limits. SETTING: University-based exercise-investigation center. METHODS: Over a 12-year period, we identified 463 patients referred to our laboratory that had their lowest resting ABI between 0.90 and 1.40. The tcpO2 on chest, buttocks, and calves were recorded during treadmill walking tests (3.2 km/h, 10% slope) in 220 ABI-b and 243 ABI-n unique consecutive patients complaining of limiting claudication (each patient's ABI was the lowest of the 2 legs). Limiting claudication was defined as the reported inability to walk 1 kilometer without stopping. A DROP index (limb tcpO2-changes minus chest tcpO2-changes from rest) below -15 mmHg was used to indicate a positive result (i.e. exercise-induced RBFI). RESULTS: Treadmill exercise showed evidence for proximal or distal RBFI, of at least one side, in 128 out of 220 patients (58.2%) and in 86 out of 243 (35.4%) patients with ABI-b and ABI-n, respectively. Isolated proximal-without-distal RBFI was found in 32 out of the 128 (25.0 %) positive tests in ABI-b and 32 out of the 86 (37.2%) positive tests in ABI-n patients. LIMITATIONS: Study limitations include the absence of systematic follow-up of diagnosed patients and absence of systematic search for cardio-respiratory co-morbid conditions. CONCLUSION: Isolated proximal-without distal RBFI is found in approximately one out of 7 patients complaining of symptom limiting claudication with a borderline or normal resting ABI. Exercise-tcpO2 may help to discriminate patients with arterial claudication that could benefit from invasive vascular investigations and procedures.

The effects of exercise modality on the incidence of plateau at VO2max.

The purpose of this study was to determine the effect of exercise modality on the incidence of plateau at VO2max. Twelve recreationally active men (age, 21·7 ± 2·3 year; mass, 74·8 ± 6·5 kg; height, 177·6 ± 5·6 cm) completed four incremental tests to volitional exhaustion, of which two were completed on a treadmill (TRE) and two were completed using a cycle ergometer (CYC). The work rate employed for CYC was 1 W·2 s(-1) from an initial loading of 100 W with cadence being maintained at 60 rpm. For TRE, the workload (gradient) increased at a rate of 0·5% · 30 s(-1) while maintaining a constant running speed of 10 kph. Throughout all the trials, VO2 was determined on a breath-by-breath basis using a precalibrated metabolic cart. The criteria adopted for determination of a plateau was a Δ VO2 over the final two consecutive 30-s sampling periods of ≤50 ml · min(-1). Averaging across the two trials per each exercise modality showed a significant difference for plateau incidence between CYC (8%) and TRE (58%) (P = 0·017). This was aligned with a significant difference in the slope of the regression line during the final 60 s of the VO2max test, CYC (99·9 ± 49·7 ml · min(-1)) and TRE (49·6 ± 42·6 ml · min(-1)) (P = 0·017). Repeat measures ANOVA of these data suggests that plateau incidence rates at VO2max differ between treadmill- and cycle ergometry-based exercises. Future studies need to address whether these response rates are replicated in well-trained athletes.

The inter- and intra-unit variability of a low-cost GPS data logger/receiver to study human outdoor walking in view of health and clinical studies.

PURPOSE: The present study evaluates the intra- and inter-unit variability of the GlobalSat® DG100 GPS data logger/receiver (DG100) when estimating outdoor walking distances and speeds. METHODS: Two experiments were performed using healthy subjects walking on a 400 m outdoor synthetic track. The two experiments consisted of two different outdoor prescribed walking protocols with distances ranging from 50 to 400 m. Experiment 1 examined the intra-unit variability of the DG100 (test-retest reproducibility) when estimating walking distances. Experiment 2 examined the inter-unit variability of four DG100 devices (unit to unit variability) when estimating walking distances and speeds. RESULTS: The coefficient of variation [95% confidence interval], for the reliability of estimating walking distances, was 2.8 [2.5-3.2] %. The inter-unit variability among the four DG100 units tested ranged from 2.8 [2.5-3.2] % to 3.9 [3.5-4.4] % when estimating distances and from 2.7 [2.4-3.0] % to 3.8 [3.4-4.2] % when estimating speeds. CONCLUSION: The present study indicates that the DG100, an economical and convenient GPS data logger/receiver, can be reliably used to study human outdoor walking activities in unobstructed conditions. This device let facilitate the use of GPS in studies of health and disease.

The incidence of plateau at VO(2max) is affected by a bout of prior-priming exercise.

The purpose of this study was to determine the effect of 6 min of prior-priming exercise on the incidence of plateau at VO(2max). Twelve trained cyclists (age, 21 ± 3 years; height, 175·0 ± 8·0 cm; weight, 69·0 ± 10·4 kg; maximal oxygen uptake (VO(2max)), 56·3 ± 6·9 ml kg(-1) min(-1)) completed three incremental tests to volitional exhaustion, which were classified as unprimed (UP), heavy-primed (HP) and severe-primed (SP), at a work rate of 1 W 2 s(-1), from an initial workload of 100 W, for the determination of VO(2max). VO(2max) trial in the HP and SP conditions was preceded by a period of 4-min unloaded cycling followed by a further 6 min of constant load cycling at Δ50% VO(2) gas exchange threshold (GET)-VO(2max) (HP) and Δ75% VO(2) GET-VO(2max) (SP). Expired air was recorded on a breath-by-breath basis during all trials. The criteria adopted for a plateau in VO(2max) was a ΔVO(2) over the final two consecutive 30-s sampling periods ≤ 2·1 ml kg(-1) min(-1). There was a significant increase in plateau responses between the UP (50%) and HP (100%) conditions (P = 0·001) coupled with a significant change in the slope of the regression line during the final 60 s of the VO(2max) test, UP and HP (P = 0·0299) and UP and SP (P = 0·0296). These data suggest that a bout of prior-priming exercise promotes an increased incidence of plateau responses at VO(2max) . It is suggested that future studies address how such an approach can be adopted without prior knowledge of GET.