Uphill Exercise Research Articles

운동 형태에 따른 노화 쥐 골격근 내 Apoptosis 작용기전에 미치는 영향

The purpose of this study is to investigate the effect of exercise type on the mechanism of apoptosis in the skeletal muscle of aging mice.BR For the experiment, it was classified into a young group (n=10), an aging group (n=10), an uphill exercise(n=10), and a downhill exercise(n=10). The exercise group performed treadmill exercises for 60 minutes, five days a week and eight weeks at exercise intensity 13 m/min, slope 10° (uphill excise) and eccentric excise 23 m/min, -16° (downhill excise).BR The results of this study are as follows.BR 1. Two forms of endurance training in skeletal muscle building in aging mice and changes in expression of oxidative stress-related factors have had a positive effect on aging mice.BR 2. In changes in expression of factors related to apoptosis in skeletal muscle and interaction of IGFBP-3 in aging mice, two forms of endurance exercise training had a positive effect on aging mice.BR 3. In changes in expression of factors related to cell growth and differentiation in skeletal muscle in aging mice and the interaction-related factors of IGFBP-3, two forms of endurance exercise training had a positive effect on aging mice.BR Therefore, the expression mechanism of IGFBP-3, a key factor of stress caused by exercise, not only presented academically meaningful results but also presented important data to suggest safer exercise methods.

Outdoor Uphill Exercise Testing for Trail Runners, a More Suitable Method?

There is extensive knowledge about uphill running on a treadmill, although paucity regarding the influence of uphill trail running on exercise capacity in runners. The purpose of this study was to compare an uphill field test with a treadmill test with 1% inclination especially considering cardiopulmonary exercise variables. The difference in those tests between a group of trail runners and a group of road runners was tested for establishing a test specifically for trail runners. Ten male endurance road runners and ten male trail runners performed one maximal incremental treadmill test with 1% inclination and a maximal incremental field test on a hill at 16% inclination which they were instructed to run up four times for three minutes, each time with a higher pace. A mobile cardiopulmonary exercise testing unit was used to measure ventilation. There were no significant differences between trail runners and road runners. The equivalence factor was comparable between both groups. was comparable for both test protocols. However, there was a significant difference between the two test protocols regarding lactate concentration, the respiratory exchange ratio, running cost, heart rate, Breathing reserve, and O2pulse. The greater lactate concentration and running cost recorded uphill indicate a higher energy demand during trail running than level road running.

Cardiorespiratory Changes During Prolonged Downhill Versus Uphill Treadmill Exercise.

Oxygen uptake (V̇O2), heart rate (HR), energy cost (EC) and oxygen pulse are lower during downhill compared to level or uphill locomotion. However, a change in oxygen pulse and EC during prolonged grade exercise is not well documented. This study investigated changes in cardiorespiratory responses and EC during 45-min grade exercises. Nine male healthy volunteers randomly ran at 75% HR reserve during 45-min exercise in a level (+1%), uphill (+15%) or downhill (-15%) condition. V̇O2 , minute ventilation (V̇E ) and end-tidal carbon dioxide (PetCO2) were recorded continuously with 5-min averaging between the 10th and 15th min (T1) and 40th and 45th min (T2). For a similar HR (157±3 bpm), V̇O2 , V̇E , and PetCO2 were lower during downhill compared to level and uphill conditions (p<0.01). V̇O2 and V̇E decreased similarly from T1 to T2 for all conditions (all p<0.01), while PetCO2 decreased only for the downhill condition (p<0.001). Uphill exercise required greater EC compared to level and downhill exercises. EC decreased only during the uphill condition between T1 and T2 (p<0.01). The lowest V̇O2 and EC during downhill exercise compared to uphill and level exercises suggests the involvement of passive elastic structures in force production during downhill. The lower cardiorespiratory response and the reduction in PetCO2 during downhill running exercise, while EC remained constant, suggests an overdrive ventilation pattern likely due to a greater stimulation of efferent neural factors.

The Effect of Uphill and Downhill Exercise Training on Myogenic Mechanism of Wnt/BMP Signaling in the Skeletal Muscle of Aged Rats

PURPOSE The purpose of this study was to determine the effect of exercise types on the Wnt/BMP signaling and the response to myogenic mechanism by downhill and uphill training in the aged rat skeletal muscles. METHODS Young and old rats were randomly assigned to control groups; young (YC) and old (OC), and two types of running training groups: old downhill exercise (ODE) and old uphill exercise (OUE). Training was progressively carried out on a treadmill at a speed of 21 m/min with a slope of +10° for uphill training vs 16 m/min with a slope of -16° for downhill training: 60 min/day, 5 days/week for 8 weeks respectively. RESULTS Downhill and uphill training significantly increased the protein levels of Wnt3a, β-catenin and LEF-1 in aged rats. On the contrary, GSK3β was reduced by running training. In addition, the expression patterns of Wnt7a, Fzd7, PKC, p-AKT, and p-mTOR in extensor digitorum longus (EDL) and soleus (SOL) muscle were significantly increased in both ODE and OUE groups. Expression patterns of BMP-2, BMP-7, and p-Smad-1/5/8 in EDL and SOL muscles were significantly increased in both ODE and OUE groups. Especially, ODE group showed more increased expression pattern than OUE group. The expression patterns of MyoD, Myf5, and Myogenin were significantly increased in both DOE and OUE groups. Myf5 and Myogenin showed more increased expression pattern in ODE group than OUE group. CONCLUSIONS The downhill and uphill exercise training may play a mediating role in increasing the expression of these reduced myogenesis related factors. Furthermore, the formation process and hypertrophy of skeletal muscle weakened due to aging can be improved and maintained. 색인어: ë ¸í™” 마우스, 내리막과 오르막 운동, GSK3β, BMP-2, BMP-7 Keywords: Aged muscles, Downhill and uphill exercise, GSK3β, BMP-2, BMP-7

SUN-538 Osteogenic Markers in Postmenopausal Diabetics Respond to Higher Mechanical Loading during Exercise after Rather Than before the Meals

Structural integrity of bones is supported by mechanical loading, energy intake, and sex hormones. It is unclear why postmenopausal (PM) diabetics experience more bone breaks despite higher body weight and positive energy balance than non-diabetics. We hypothesized that greater bone fragility in PM diabetics may result from peripheral insulin resistance and reduced nutrient access to the bone. We engaged 15 diabetic women, age 57.7y, BMI 27.2 kg/m2, in two of five day-long experiments : SED (no exercise), UBM and UAM (40 min of uphill treadmill exercise, respectively one h before, or one h after eating two daily isocaloric meals at 10 and 17 h and containing 50% carbohydrate, 15% protein, and 25% fat), and DBM and DAM (downhill exercise at -6o slope with meals and exercise timed the same way). Markers of bone formation osteocalcin (OCN) and CICP (c-terminal propeptide of type I collagen) and of resorption, CTX (c-terminal telopeptide of type I collagen), anabolic growth hormone and catabolic cortisol were measured hourly in the serum. Glucose and insulin were measured to assess insulin resistance by the homeostatic HOMA-IR method from 7-h postprandial (PP) insulin and glucose areas under the curve (AUCs).Peak ground-reaction forces (GRFs) were monitored with Novel Pedar mechanosensitive shoe insoles, and physical effort was assessed as percent of VO2max with a metabolic cart. During uphill trials, mean effort was 75.2% , and GRFs were 780.7 N. During downhill trials, the corresponding values were 47.9% of VO2max and 1104.8 N (both >0.05). A similar CTX decline in all 5 trials after the 10h meal was larger than after the 17 h meal (7h negative PP AUCs: 1.52 vs 1.37 ng/ml*h, respectively) and coincided with PP insulin AUCs. CICP rise in DAM trial was 44% greater than in DBM trial after 10h meal (AUCs, 685.9 vs 384.1 ng/ml*h, respectively) and produced a 40 percent greater osteogenic CICP/CTX ratio after 10h meal in the in the DAM than DBM trial. No group difference was seen in brief postprandial serum glucose rises, while PP insulin was highest in UBM and SED trials and low in the two downhill and UAM trials. HOMA-IR in the two downhill trials (355.6) was reduced to 47% of that in two uphill trials (759.1) and to 62% of the SED trial (571.4). Circulating OCN and hormones showed no clear relationship to either the loading or meal-exercise timing patterns. We conclude that In PM diabetics, downhill (as opposed to uphill) exercise after a meal conveys a clear benefit in stimulating a bone- forming CICP, more so after the 10h than the 17 h meal. Meal eating, independently of exercise, lowers the bone resorption marker CTX. In diabetic PM women, Increased GRFs of downhill exercise reduce HOMA-IR insulin resistance to high-carbohydrate meals more than uphill exercise or SED control. Postprandial downhill exercise has the highest osteogenic potential.

Accuracy of the energy expenditure during uphill exercise measured by the Waist-worn ActiGraph

Background/objectiveThe application of Micro-Electro-Mechanical Sensors (MEMS) as measurements of energy expenditure (EE) has certain disadvantages. For example, the inertial sensors cannot easily distinguish changes in ground slope during walking/running conditions, so the accuracy of EE calculation is biased. To resolve this issue, heart rate (HR) and heart rate reserve (HRR) were used as compensatory factors respectively to correct the classical empirical formula of the accelerometer analyzer for EE in this study. MethodsTo explore the improvement of the accuracy of EE during uphill exercise and compare the correction levels between HR and HRR, oxygen uptake was used as a criterion measure (CM). Thirty healthy adult males wore an ActiGraph GT3X with the Polar HR monitor and Vmax indirect calorimeter during twelve treadmill activities (3 gradients and 4 speeds). ResultsWhen the slopes were increased by 0%, 3%, and 6%, the measurement accuracy of the accelerometers, calculated by intraclass correlation coefficient (ICC), decreased by 0.877, 0.755, and 0.504, respectively (p < 0.05). The HR and HRR parameters of linear regression were used to correct the classical formula. The results showed that HR had higher coefficients of determination (R2) (0.801, 0.700, and 0.642 respectively) and ICCs (0.887, 0.825, and 0.785 respectively) than did the accelerometer outputs. HRR showed the highest coefficients of determination (R2) (0.821, 0.728, and 0.656 respectively) and ICCs (0.901, 0.844, and 0.795 respectively). ConclusionsThrough adding HRR parameters, the accuracy of the classical prediction formula EE was significantly improved during walking/running on sloping ground.

Larger strength losses and muscle activation deficits in plantar flexors induced by backward downhill in reference to distance-matched forward uphill treadmill walk

We tested the hypothesis that backward downhill walking (eccentric component) impairs both voluntary activation and muscle contractile properties in the plantar flexors and delays recovery as compared to a gradient and distance-matched uphill walk. Fourteen males performed two 30-min walking exercises (velocity: 1 m/ s; grade: 25%; load: 12% of body weight), one downhill (DW) and one uphill (UP), in a counterbalanced order, separated by 6 weeks. Neuromuscular test sessions were performed before, after, 24-, 48- and 72-h post-exercise, including motor nerve stimulations during brief (5 s) and sustained (1 min) maximal isometric voluntary contractions of the plantar flexors. DW (−18.1 ± 11.1%, P < .001), but not UP (−6.0 ± 7.7%, P =.15), decreased torque production during brief contractions for at least three days post-exercise (P < .05). Voluntary activation during brief contractions decreased after DW (P < .05), but not UP, and recovered by 24 h. Both UP (−9.3 ± 9.0%, P = .024) and DW (−25.6 ± 10.3%, P < .001) decreased torque production during sustained contractions but voluntary activation (P = .001) was lower in DW than UP. Peak twitch torque and maximum rates of torque development and relaxation were equally reduced after UP and DW (P < .05), and recovered by 24 h. DW induced an increase in muscle soreness with peak values observed 48 h post-walking (P < .001), whereas post-UP exercise changes were non-significant (all P > .05). Using a direct comparison, the capacity to drive the plantar flexors during sustained contractions remains sub-optimal during the three-day recovery period in response to non-exhaustive, downhill backward walking in reference to an uphill exercise matched for distance covered.

Secondary Full Title: Effects of high intensity interval training in plain and uphill regarding physical performance

As the number of HIITs is increasing in competitive and non-competitive sports, the risk of injuries and overload is increasing. There are no scientific data to support specific recommendations in regard to intensity, duration, number of intervals and gradient for HIIT that result in improved muscular parameters in athletes. Therefore the aim of this study was to compare HIIT in plain and uphill exercise, with respect to exercise tolerance and improvements in performance (VO2max and 800 m running time in the plain and uphill). 17 well-trained sport students (10females, 7 males; Ø VO2max: 53.7 ml/min/kg) were randomly assigned to the plain group (plain; GE) (n = 8) or the uphill group (hill, GB) (n = 9). In the four weeks of training, all subjects completed 14 HIIT sessions. Each session consisted of 8 × 2 min running at 90 - 95 % of the maximal heart rate (HRmax), separated by 2 min recovery periods (work/rest ratio: 1:1). Before the intervention phase, subjects performed treadmill spirometry, a 800 m field test in the plain, as well as an 800 m uphill field test to determine baseline performance. One week after the intervention period, all subjects completed a retest of all measurements and tests. After the intervention, all subjects completed a questionnaire by giving their level of perceived exertion during training, using the BORG scale. In GE, three subjects dropped out of the study because of overtraining. In GB, two subjects did not complete the study because of time constraints. The evaluation of the perceived exertion of the training in flat terrain showed a trend (p = 0.08; t = - 1.96) towards being perceived as more exhausting then in hilly terrain. A four week HIIT showed significant improvements in VO2max by 5.2 % (p = 0.02; t = - 2.76), and a reduction in the running time in the plain by 4.6 % (p = 0.01; t = 3.48) and uphill by 6.3 % (p = 0.02; t = 2.77). No significant group effect was detected. In this study, the application of HIIT leads to significant improvements in the performance of well-trained athletes. There is no evidence that the mode of training influenced the running improvements. However, uphill training tends to be better tolerated by the athletes.

The effects of downhill and uphill exercise training on osteogenesis-related factors in ovariectomy-induced bone loss.

[Purpose]Recent evidence suggests that regular exercise training plays a decisive role in maintaining homeostasis and promoting muscle and skeletal formation. However, the effect of downhill exercise training on osteogenesis-related factors is not well understood.[Methods]Thus, we investigated the effect of uphill and downhill training on ovariectomy (OVX)-induced bone loss. After ovary removal, the exercise method performed included uphill (16 m/min, +15°) and downhill training (16 m/min, –15°) for 60 min/day and 5 days/week, respectively, for 8 weeks.[Results]Our results showed that both uphill and downhill training significantly decreased the body weight, total cholesterol, and creatine kinase (CK) levels in the context of OVX-induced bone loss. On the contrary, levels of an osteogenesis indicator, osteocalcin and alkaline phosphatase were elevated. Consequently, the uphill and downhill training reduced OVX- induced bone loss in the distal femoral metaphysis. Likewise, the bone microstructure in OVX-induced bone loss was enhanced upon training. In particular, the inhibition of RANKL-induced osteoclast formation and osteoclast-specific gene expression improved upon downhill training compared to uphill training.[Conclusion]These results suggest that the uphill and downhill exercise types appeared to positively affect the expression of osteogenesis-related factors along with bone density and microstructure. Particularly, the downhill training has more beneficial effects on the maintenance of homeostasis during bone formation.

Influence of Accelerometer Placement and/or Heart Rate on Energy Expenditure Prediction during Uphill Exercise

ABSTRACTStudies using a triaxial accelerometer and heart rate (HR) simultaneously for estimating energy expenditure (EE) during uphill exercise are rare. Exploring the optimal location for placing the accelerometer for predicting EE during uphill exercise is essential. Sixteen healthy male participants (M ± SEM; age 25.00 ± 0.61 years; body weight 74.13 ± 2.51 kg; body height 1.74 ± 0.01 m; body mass index 24.30 ± 0.63 kg/m2) exercised on a treadmill under 12 conditions (4 speeds and 3 gradients) on 3 days. Triaxial accelerometers, an HR recorder, and a metabolic measurement system were simultaneously used. Accelerometer outputs from various anatomical locations (upper arm, chest, lower back, waist, thigh, and instep) showed significant positive correlations with EE (0.819, 0.846, 0.816, 0.820, 0.672, and 0.669, respectively; p < .05). The linear regression equation for changes in HR showed the highest coefficient of determination (r2) of .837 with 87.9% reliability. When the HR signal was included, the r2 value (> .842) and reliability (87.9%) between the accelerometer outputs and EE improved. Accelerometer outputs from the waist position alone provide highly accurate EE values. Using both accelerometer outputs and HR for EE estimation during uphill exercise is feasible and improves the accuracy of EE prediction.

Mitochondrial function following downhill and/or uphill exercise training in rats.

The goal of this study was to compare the effects of downhill (DH), uphill (UH), and UH-DH exercise training, at the same metabolic rate, on exercise capacity and skeletal muscle mitochondrial function. Thirty-two Wistar rats were separated into a control and 3 trained groups. The trained groups exercised for 4 weeks, 5 times per week at the same metabolic rate, either in UH, DH, or combined UH-DH. Twenty-four hours after the last training session, the soleus, gastrocnemius, and vastus intermedius muscles were removed for assessment of mitochondrial respiration. Exercise training, at the same metabolic rate, improved maximal running speed without specificity for exercise modalities. Maximal fiber respiration was enhanced in soleus and vastus intermedius in the UH group only. Exercise training, performed at the same metabolic rate, improved exercise capacity, but only UH-trained rats enhanced mitochondrial function in both soleus and vastus intermedius skeletal muscle. Muscle Nerve 54: 925-935, 2016.

The Effects of Inclination (Up and Down) of the Treadmill on the Electromyogram Activities of the Forelimb and Hind limb Muscles at a Walk and a Trot in Thoroughbred Horses.

ABSTRACTIt is important to know the effects of the inclination of a slope on the activity of each muscle, because training by running on a sloped track is commonly used for Thoroughbred racehorses. The effects of incline (from −6 to +6%) on the forelimbs and hind limbs during walking and trotting on a treadmill were evaluated by an integrated electromyogram (iEMG). The muscle activities in the forelimbs (5 horses) and hind limbs (4 horses) were measured separately. Two stainless steel wires were inserted into each of the brachiocephalicus (Bc), biceps brachii (BB), splenius (Sp), and pectoralis descendens (PD) in the forelimb experiment and into the longissimus dorsi (LD), vastus lateralis (VL), gluteus medius (GM), and biceps femoris (BF) in the hind limb experiment. The EMG recordings were taken at a sampling rate of 1,000 Hz. At a walk, the iEMG values for the forelimb were not significantly different under any of the inclinations. In the hind limb, the iEMG values for the GM and BF significantly decreased as the inclination decreased. At a trot, the iEMG values for the Bc in the forelimb significantly decreased as the inclination of the treadmill decreased. In the hind limb, the iEMG values for the LD, GM, and BF significantly decreased as the inclination decreased. Uphill exercise increased the iEMG values for the Bc, LD, GM, and BF, while downhill exercise resulted in little increase in the iEMG values. It was concluded that the effects of inclination on the muscle activities were larger for the uphill exercises, and for the hind limb muscles compared with the forelimb muscles.

Exercise Training Reverses Skeletal Muscle Atrophy in an Experimental Model of VCP Disease

BackgroundThe therapeutic effects of exercise resistance and endurance training in the alleviation of muscle hypertrophy/atrophy should be considered in the management of patients with advanced neuromuscular diseases. Patients with progressive neuromuscular diseases often experience muscle weakness, which negatively impact independence and quality of life levels. Mutations in the valosin containing protein (VCP) gene lead to Inclusion body myopathy associated with Paget's disease of bone and frontotemporal dementia (IBMPFD) and more recently affect 2% of amyotrophic lateral sclerosis (ALS)-diagnosed cases.Methods/Principle FindingsThe present investigation was undertaken to examine the effects of uphill and downhill exercise training on muscle histopathology and the autophagy cascade in an experimental VCP mouse model carrying the R155H mutation. Progressive uphill exercise in VCPR155H/+ mice revealed significant improvement in muscle strength and performance by grip strength and Rotarod analyses when compared to the sedentary mice. In contrast, mice exercised to run downhill did not show any significant improvement. Histologically, the uphill exercised VCPR155H/+ mice displayed an improvement in muscle atrophy, and decreased expression levels of ubiquitin, P62/SQSTM1, LC3I/II, and TDP-43 autophagy markers, suggesting an alleviation of disease-induced myopathy phenotypes. There was also an improvement in the Paget-like phenotype.ConclusionsCollectively, our data highlights that uphill exercise training in VCPR155H/+ mice did not have any detrimental value to the function of muscle, and may offer effective therapeutic options for patients with VCP-associated diseases.

Changes in circulating microRNAs levels with exercise modality

Here, we studied muscle-specific and muscle-related miRNAs in plasma of exercising humans. Our aim was to determine whether they are affected by eccentric and/or concentric exercise modes and could be biomarkers of muscle injuries or possible signaling molecules. On two separate days, nine healthy subjects randomly performed two 30-min walking exercises, one downhill (high eccentric component) and one uphill (high concentric component). Perceived exertion and heart rate were higher during the uphill exercise, while subjective pain and ankle plantar flexor strength losses within the first 48-h were higher following the downhill exercise. Both exercises increased serum creatine kinase and myoglobin with no significant differences between conditions. Plasma levels of circulating miRNAs assessed before, immediately after, and at 2-, 6-, 24-, 48-, and 72-h recovery showed that 1) hsa-mir-1, 133a, 133b, and 208b were not affected by concentric exercise but significantly increased during early recovery of eccentric exercise (2 to 6 h); 2) hsa-mir-181b and 214 significantly and transiently increased immediately after the uphill, but not downhill, exercise. The muscle-specific hsa-mir-206 was not reliably quantified and cardiac-specific hsa-mir-208a remained undetectable. In conclusion, changes in circulating miRNAs were dependent on the exercise mode. Circulating muscle-specific miRNAs primarily responded to a downhill exercise (high eccentric component) and could potentially be alternative biomarkers of muscle damage. Two muscle-related miRNAs primarily responded to an uphill exercise (high exercise intensity), suggesting they could be markers or mediators of physiological adaptations.

The weighted walking test as an alternative method of assessing aerobic power

The aim of the present study was to determine maximal oxygen uptake ([Vdot]O2max) directly during uphill walking exercise and to compare these values with those achieved during running and cycling exercise. Forty untrained students (20 males and 20 females) took part in three exercise tests. The running test was performed on a horizontal treadmill and the speed was gradually increased by 0.3 m · s−1 every 3 min. The walking test was conducted on a treadmill inclined at 12% (speed of 1.8 m · s−1). The load was further increased every 3 min by the addition of a mass of one-twentieth of the body mass of the participant (plastic containers filled with water and added to a backpack carried by the participant). During the bicycle ergometry test, the workload was increased by 20 W every 2 min. All tests were performed until volitional exhaustion. During all tests, oxygen uptake, minute ventilation, tidal volume, respiratory frequency, heart rate, hydrogen ion concentration, base excess, and blood lactate concentration were analysed. The Pearson correlation coefficients between the weighted walking test and the commonly applied running and bicycle ergometry tests indicate a strong association with the new test in evaluating maximal oxygen uptake. The negligible differences in [Vdot]O2max between the three tests for the male participants (running: 61.0 ml · kg−1 · min−1; walking: 60.4 ml · kg−1 · min−1; cycling: 60.2 ml · kg−1 · min−1), and the fact that the females achieved better results on the walking test than the cycle ergometer test (running: 45.0 ml · kg−1 · min−1; walking: 42.6 ml · kg−1 · min−1; cycling: 40.1 ml · kg−1 · min−1), confirm the suitability of the new method for evaluating aerobic power. The weighted walking test could be useful in the assessment of aerobic power in individuals for whom running is not advised or is difficult. In addition, the new test allows for determination of [Vdot]O2max on small treadmills with a limited speed regulator, such as those found in specialist physiotherapy and fitness centres.

Effect of uphill exercise on equine superficial digital flexor tendon forces at trot and canter

One cause of overstrain injury to the superficial digital flexor tendon (SDFT) in horses is the force loaded on the SDFT during repeated running. Therefore, decreasing this force may reduce SDFT injury. It has been reported that strain on the SDFT decreases with a toe-wedge shoe. Uphill courses are used for training of racehorses, and the angle of hoof-sole to the horizon during uphill running is similar to that of the toe-wedge shoe. To determine the effects of uphill exercise on the force on the SDFT during trotting and cantering. Arthroscopically implantable force probes (AIFP) were implanted into the SDFT of the left or right forelimb of 7 Thoroughbred horses and AIFP output recorded during trotting and cantering on a treadmill inclined at slopes of 0, 3 or 8%, and then 0% again. Superficial digital flexor tendon force was calculated as a relative value, with the amplitude of AIFP output voltage at initial 0% slope equal to 100. Out of 14 sets of experiments, AIFP data were analysed successfully in 9 at the trot, in 3 at the canter in the trailing forelimb on a slope of 3 and 8%, and in 2 at the canter in the leading forelimb on a slope of 3%. Increasing the incline from 0-8% tended to decrease peak force in the SDFT at the trot, and in the trailing forelimb at the canter. However, force in the SDFT was unchanged in the leading forelimb at the canter on the 3% incline. The force in the SDFT trotting or cantering uphill is unchanged or lower than that loaded at the same speed on a flat surface. Because at similar speeds the workload for uphill exercise is greater than on the flat, uphill running increases exercise intensity without increasing force in the SDFT. Uphill exercise may reduce the risk of SDFT injury as both running speed and SDFT force are decreased on an incline as compared to the flat, even when exercise intensity is the same. Further study is needed to confirm these findings at canter in a larger population of horses.

Effects of Uphill Exercise on Digestible Energy Intake and Energy Expenditure during Exercise in Yearling Horses

The objectives of this study were to evaluate the digestible energy intake and energy expenditure in yearling horses on different training protocols (uphill- and level-track exercise training protocols). Twenty-four thoroughbred yearlings (12 males and 12 females, aged 27.0±0.9 months) were divided into two groups based on their training on two different tracks: the uphill (with a gradient of about 3%) training group (uphill training) and the level training group (level training). The digestible energy (DE) intake and energy expenditure (EE) during exercise were measured in both the groups. It was found that the DE intake in the uphill training and the level training groups was 35.1±3.1 and 36.9±4.8 Mcal/day, respectively. The EE during exercise in the two groups was 3.05±0.51 and 2.07 ±0.56 Mcal, respectively. Thus, there was a significant difference in the EE (p<0.05), but not in the DE intake between the animals of the two training groups. The EE for a given intensity of exercise was greater in the uphill training group than in the level training group, but the DE intake was not affected by the exercise intensity. The DE intake was not generally affected by the intensity of exercise in this study, but a daily negative gain of body weight was observed in the uphill training group, particularly in the females. Thus, the energy requirement may be higher in yearlings undergoing uphill training than in those undergoing level training. (Asian-Aust. J. Anim. Sci. 2004. Vol 17, No. 7 : 973-979)

Biomechanical implications of uphill training on the aetiology of tendinitis.

It has been reported that a small decrease in the strain in the superficial digital flexor tendon (SDFT) occurs if the toe is raised during walking. Although walking on a slope appears similar to raising the toe, it is unclear whether uphill exercise decreases the strain in the SDFT. Because the force or strain on tendons is one of the important factors leading to tendon stress injury, we hypothesised that reducing the force in the SDFT during exercise may prevent tendinitis. The purpose of this study was to determine the effects of treadmill inclination on the force in the SDFT in the walking horse. 'Arthroscopically implantable force probes' (AIFP) were implanted into the SDFT of the forelimb of 4 horses. The AIFP output was recorded during walking on a treadmill inclined at 0%, 3%, 8% and then 0% again. When the inclination increased from 0 to 8%, the first peak of force in the SDFT decreased significantly, the second increased significantly, but the maximal force and the area under the force-time curve did not change. In conclusion, uphill walking on an inclined treadmill did not decrease the maximal force in the SDFT or the area under the force-time curve, however, the patterns of force were altered. Future research should focus on the force distributions of tendons and ligaments at faster gaits, because the effects of a change in hoof angle and slope may be greater at faster gaits.

Adverse Effect of Additional Weight on Exercise Against Gravity in Patients With Chronic Obstructive Airways Disease

The effects of an acute, artificially simulated increase in body weight on exercise performance were examined in 14 patients of normal weight (mean (SD) body mass index 22.3 (2.7)), age 61 (8) years) with chronic obstructive airways disease (FEV1 1.2 (0.5) 1; vital capacity (VC) 2.9 (0.6) 1), and in six normal subjects with similar age and sex distribution. The patients performed a six minute walking test and a symptom limited step climbing test both with and without an additional 10 kg weight (two leaded aprons). The normal subjects performed a step test with and without the additional weight. Ventilation (VE) and oxygen consumption (VO2) were measured during step climbing. Resting spirometric values were not altered by the additional weight. In the patients the median number of steps climbed fell from 67.5 when they were unweighted to 44.5 when they were weighted. Mean VE and VO2 were increased during weighted step climbing by 14% and 13% but the maximum levels of VE and VO2 achieved were similar during unweighted and weighted exercise (VE 36.8 (8.6) and 37.3 (10.2) 1 min-1, VO2 1.35 (0.3) and 1.41 (0.4) 1 min-1 respectively). The normal subjects were readily able to complete 150 steps both with and without the additional weight. In the patients the six minute walking distance fell only slightly with the extra weight, from 554 (SD 61) to 540 (62) m. A subsidiary study was carried out in six healthy younger subjects in which VE and VO2 were measured during a 5.6 km/h six minute treadmill walk at zero incline. The additional weight did not alter VE or VO2 during exercise. In conclusion, a small acute increase in body weight substantially worsened the already reduced uphill exercise performance in patients with chronic obstructive airways disease because of its effect on ventilation and oxygen consumption. These results suggest that modest weight loss might benefit patients with chronic obstructive airways disease even though they may be only slightly above their ideal body weight.