Cancer Survival Through Lifestyle Change (CASTLE): a Pilot Study of Weight Loss

Background

Excess weight is a strong predictor of incident breast cancer (BC) and survivorship. A limited number of studies comparing strategies for promoting successful weight loss in women with remitted BC exist.

Purpose

CASTLE was a pilot study comparing the effectiveness/feasibility of in-person and telephonic behavioral-based lifestyle weight loss interventions in BC survivors.

Method

Fifty-two overweight/obese women (BMI?=?25–45 kg/m²) with remitted BC (stages I–IIIa) who recently completed cancer treatment were assigned to either an in-person group (n?=?24) or an individual telephone-based condition (n?=?11). Both interventions focused on increasing physical activity and reducing caloric intake. The phase I intervention lasted 6 months. The in-person condition received 16 group-based sessions, and the telephone condition received intervention calls approximately weekly. Phase II lasted 6 months (e.g., months 6–12), and all participants received monthly intervention calls via telephone.

Results

Participants were predominately Caucasian (80 %) with a mean age of 52.8 (8.0) years and BMI of 31.9 (5.4) kg/m². Mixed models ANOVAs showed significant within group weight loss after 6 months for both the in-person (?3.3 kg?±?4.4, p?=?0.002) and the telephonic (?4.0 kg?±?6.0, p?=?0.01) conditions with no between group differences. During phase II, the in-person group demonstrated significant weight regain (1.3 kg?±?1.7, p?=?0.009).

Conclusion

Our pilot study findings demonstrated that telephone-based behavioral weight loss programs are effective and feasible in BC survivors and that telephonic programs may have advantages in promoting weight loss maintenance.     

Resistance exercise training-induced decrease in circulating inflammatory CD14+CD16+ monocyte percentage without weight loss in older adults

Purpose

Exercise training reduces systemic inflammation in weight-stable people, but concurrent diet-induced body weight loss is not well studied. We hypothesized that resistance training would decrease inflammatory monocyte percentage and improve biomarkers associated with disease risk, independent of weight loss.

Methods

Forty physically inactive (PI) subjects (58.0 ± 5.7 years; BMI 30.1 ± 4.3 kg m^?2) completed baseline testing, and 26 of these subjects completed 12-week of resistance training exercises while consuming either their usual, weight-maintenance diet (RE, n = 14) or an energy-restricted diet (RE–ER, n = 12). Nine physically active (PA) subjects served as a comparison group (60.1 ± 6.1 years; BMI 25.8 ± 3.1 kg m^?2).

Results

At baseline, circulating CD14+CD16+ monocyte percentage, C-reactive protein, and cholesterol were higher in PI vs. PA. Post-intervention, RE subjects had a ~35 % decrease in circulating CD14+CD16+, and a lower LPS-stimulated TNFα and IL-6 production, while RE–ER subjects had lower cholesterol than RE.

Conclusions

These findings indicate that resistance training is an effective means for older, overweight adults to reduce systemic inflammation. The unexpected lack of response with concurrent energy restriction underscores the need for further research on the use of resistance training and diet to reduce inflammation.     

Central and peripheral anti-inflammatory effects of maprotiline on carrageenan-induced paw edema in rats

Objective

To explore the site of action of maprotiline, as an atypical antidepressant, on carrageenan-induced paw edema.

Subjects

Male Wistar rats were used.

Methods

Firstly, the anti-inflammatory effect of systemic maprotiline (12.5, 25 and 50 mg kg^?1) was assessed using a paw edema model. Secondly, different doses of maprotiline were administrated intracerebroventricularly, intrathecally and locally before carrageenan challenge. Finally, we tried to reverse the anti-inflammatory effect of maprotiline by propranolol (10 mg kg^?1), prazosin (4 mg kg^?1), yohimbine (10 mg kg^?1), naloxone (4 mg kg^?1) and mifepristone (5 mg kg^?1).

Results

Systemic, intracerebroventricular and subplantar application of maprotiline significantly inhibited peripheral edema, but intrathecal maprotiline did not alter the degree of paw swelling. The applied antagonists failed to change the anti-inflammatory activity of maprotiline.

Conclusion

These results demonstrate that maprotiline has a potent anti-inflammatory effect and this effect is linked to the peripheral and supraspinal actions of the drug.     

Self-Weighing Frequency Is Associated with Weight Gain Prevention over 2 Years Among Working Adults

Background

Little is known about the association between self-weighing frequency and weight gain prevention, particularly in worksite populations.

Purpose

The degree to which self-weighing frequency predicted 2-year body weight change in working adults was examined.

Method

The association between self-weighing frequency (monthly or less, weekly, daily, or more) and 24-month weight change was analyzed in a prospective cohort analysis (n?=?1,222) as part of the larger HealthWorks trial.

Results

There was a significant interaction between follow-up self-weighing frequency and baseline body mass index. The difference in weight change ranged from ?4.4?±?0.8?kg weight loss among obese daily self-weighers to 2.1?±?0.4?kg weight gain for participants at a healthy weight who reported monthly self-weighing.

Conclusion

More frequent self-weighing seemed to be most beneficial for obese individuals. These findings may aid in the refinement of self-weighing frequency recommendations used in the context of weight management interventions.     

Self-selected speeds and metabolic cost of longboard skateboarding

Purpose

The purpose of this study was to determine self-selected speeds, metabolic rate, and gross metabolic cost during longboard skateboarding.

Methods

We measured overground speed and metabolic rate while 15 experienced longboarders traveled at their self-selected slow, typical and fast speeds.

Results

Mean longboarding speeds were 3.7, 4.5 and 5.1 m s^?1, during slow, typical and fast trials, respectively. Mean rates of oxygen consumption were 24.1, 29.1 and 37.2 ml kg^?1 min^?1 and mean rates of energy expenditure were 33.5, 41.8 and 52.7 kJ min^?1 at the slow, typical and fast speeds, respectively. At typical speeds, average intensity was ~8.5 METs. There was a significant positive relationship between oxygen consumption and energy expenditure versus speed (R ² = 0.69 (P < 0.001), and R ² = 0.78 (P < 0.001), respectively). The gross metabolic cost was ~2.2 J kg^?1 m^?1 at the typical speed, greater than that reported for cycling and ~50 % smaller than that of walking.

Conclusion

These results suggest that longboarding is a novel form of physical activity that elicits vigorous intensity, yet is economical compared to walking.     

Effects of a Cognitive–Behaviorally Based Physical Activity Treatment for 4- and 5-Year-Old Children Attending US Preschools

Background

Inadequate volumes of physical activity may be associated with the increases in inappropriately high weight in children of 5 years of age and younger. Preschools have typically lacked sufficient time in daily physical activity.

Purpose

A preschool-administered physical activity treatment based on social cognitive and self-efficacy theory (Start For Life) was tested for its association with increased physical activity and reduced body mass index (BMI).

Methods

Data from accelerometer and BMI assessments over a 9-month preschool year (18 treatment and 8 control classes of 17 to 20 children each; mean age?=?4.4 years) were used to contrast the behaviorally based treatment of 30 min per day with a usual care condition of the same duration. The sample was primarily African-American. Preschool teachers administered all processes.

Results

The Start For Life treatment was associated with a significantly greater percentage of the preschool day in moderate-to-vigorous and vigorous physical activity (approximately 30 min per week more), with sedentary time unaffected. The treatment was also associated with a significant reduction in BMI, with effect sizes greatest in overweight and obese children.

Conclusions

Although results were positive in contrast to usual care and other related interventions, the specific sample requires that the Start For Life treatment undergo sufficient replication to increase confidence in generalizability of the findings to others. Although reduction in sedentary time may require a different strategy, the practical application of the present treatment suggests possibilities for addressing overweight through increasing moderate-to-vigorous physical activity in preschool settings.     

Energy expenditure of extreme competitive mountaineering skiing

Purpose

Multi-hour ski mountaineering energy balance may be negative and intake below recommendations.

Methods

Athletes on the ‘Patrouille des Glaciers’ racecourses (17 on course Z, 27 km, +2,113 m; 11 on course A, 26 km, +1,881 m) volunteered. Pre-race measurements included body mass, stature, VO_2max, and heart rate (HR) vs VO₂ at simulated altitude; race measurements HR, altitude, incline, location, and food and drink intake (A). Energy expenditure (EE) was calculated from altitude corrected HR derived VO₂.

Results

Race time was 5 h 7 min ± 44 min (mean ± SD, Z) and 5 h 51 min ± 53 min (A). Subjects spent 19.2 ± 3.2 MJ (Z), respectively, 22.6 ± 2.9 MJ (A) during the race. Energy deficit was ?15.5 ± 3.9 MJ (A); intake covered 20 ± 7 % (A). Overall energy cost of locomotion (EC) was 9.9 ± 1.3 J m^?1 kg^?1 (Z), 8.0 ± 1.0 J m^?1 kg^?1 (A). Uphill EC was 11.7 ± 1 J m^?1 kg^?1 (Z, 13 % slope) and 15.7 ± 2.3 J m^?1 kg^?1 (A, 19 % slope). Race A subjects lost ?1.5 ± 1.1 kg, indicating near euhydration. Age, body mass, gear mass, VO_2max and EC were significantly correlated with performance; energy deficit was not.

Conclusions

Energy expenditure and energy deficit of a multi-hour ski mountaineering race are very high and energy intake is below recommendations.     

Hypervolemia induced by fluid ingestion at rest: effect of sodium concentration

Purpose

Sodium drink is used as a countermeasure against body fluid loss. However, high concentrations of sodium may cause gastrointestinal upset (e.g., diarrhea). We sought to determine the sodium concentration that induces hypervolemia with a minimal risk of gastrointestinal disturbance.

Methods

Eight healthy active males rested in a chair and ingested a given amount (16?17 ml kg body mass^?1) of water (W) or solution containing 60, 120 or 180 mmol l^?1 Na⁺ (60, 120 and 180Na trials) in 6 equal portions at 10 min intervals. To standardize their hydration status, subjects consumed the same meal and water 2 h before each trial. Drink trials were performed on separate days, and the order was randomized. The change in plasma volume (PV) from pre-drink status was estimated from the hemoglobin concentration and hematocrit every 30 min for 150 min after initiation of drinking.

Results

Subjects began trials in a euhydrated state, as reflected by their plasma osmolality (in mmol l^?1: W, 289.4 ± 1.4; 60Na, 287.0 ± 3.5; 120Na, 287.6 ± 2.3; 180Na, 288.9 ± 3.3). At 120 min, PV had not increased from the pre-drink value in the W (?0.8 ± 4.5 %) or 60Na (2.4 ± 4.9 %) trials, but it increased to similar degrees in the 120Na (7.2 ± 4.6 %) and 180Na (9.4 ± 6.6 %) trials. No diarrhea was reported in the W or 60Na trials, but it was reported in the 120Na (n = 1) and 180Na (n = 6) trials.

Conclusions

Beverages containing 120 mmol l^?1 Na⁺ induce hypervolemia with a minimum incidence of gastrointestinal problems.     

Influence of blood donation on the incidence of plateau at \dot{V}{\text{O}} 2max

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 $\dot{V}{\text{O}}$ _2max.

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 cm³). 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, $\dot{V}{\text{O}}$ ₂ was determined on a breath-by-breath basis using a pre-calibrated metabolic cart. The criteria for plateau determination was a ? $\dot{V}{\text{O}}$ ₂ ≤ 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 $\dot{V}{\text{O}}$ _2max (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 $\dot{V}{\text{O}}$ _2max 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 $\dot{V}{\text{O}}$ _2max.     

Enhancing performance during inclined loaded walking with a powered ankle–foot exoskeleton

Purpose

A simple ankle–foot exoskeleton that assists plantarflexion during push-off can reduce the metabolic power during walking. This suggests that walking performance during a maximal incremental exercise could be improved with an exoskeleton if the exoskeleton is still efficient during maximal exercise intensities. Therefore, we quantified the walking performance during a maximal incremental exercise test with a powered and unpowered exoskeleton: uphill walking with progressively higher weights.

Methods

Nine female subjects performed two incremental exercise tests with an exoskeleton: 1 day with (powered condition) and another day without (unpowered condition) plantarflexion assistance. Subjects walked on an inclined treadmill (15 %) at 5 km h^?1 and 5 % of body weight was added every 3 min until exhaustion.

Results

At volitional termination no significant differences were found between the powered and unpowered condition for blood lactate concentration (respectively, 7.93 ± 2.49; 8.14 ± 2.24 mmol L^?1), heart rate (respectively, 190.00 ± 6.50; 191.78 ± 6.50 bpm), Borg score (respectively, 18.57 ± 0.79; 18.93 ± 0.73) and \(\dot{V}{\rm O}_{2}\) peak (respectively, 40.55 ± 2.78; 40.55 ± 3.05 ml min^?1 kg^?1). Thus, subjects were able to reach the same (near) maximal effort in both conditions. However, subjects continued the exercise test longer in the powered condition and carried 7.07 ± 3.34 kg more weight because of the assistance of the exoskeleton.

Conclusion

Our results show that plantarflexion assistance during push-off can increase walking performance during a maximal exercise test as subjects were able to carry more weight. This emphasizes the importance of acting on the ankle joint in assistive devices and the potential of simple ankle–foot exoskeletons for reducing metabolic power and increasing weight carrying capability, even during maximal intensities.     

Exercise volume and intensity: a dose–response relationship with health benefits

Introduction

The health benefits of exercise are well established. However, the relationship between exercise volume and intensity and health benefits remains unclear, particularly the benefits of low-volume and intensity exercise.

Purpose

The primary purpose of this investigation was, therefore, to examine the dose–response relationship between exercise volume and intensity with derived health benefits including volumes and intensity of activity well below international recommendations.

Methods

Generally healthy, active participants (n = 72; age = 44 ± 13 years) were assigned randomly to control (n = 10) or one of five 13-week exercise programs: (1) 10-min brisk walking 1×/week (n = 10), (2) 10-min brisk walking 3×/week (n = 10), (3) 30-min brisk walking 3×/week (n = 18), (4) 60-min brisk walking 3×/week (n = 10), and (5) 30-min running 3×/week (n = 14), in addition to their regular physical activity. Health measures evaluated pre- and post-training including blood pressure, body composition, fasting lipids and glucose, and maximal aerobic power (VO₂max).

Results

Health improvements were observed among programs at least 30 min in duration, including body composition and VO₂max: 30-min walking 28.8–34.5 mL kg^?1 min^?1, 60-min walking 25.1–28.9 mL kg^?1 min^?1, and 30-min running 32.4–36.4 mL kg^?1 min^?1. The greater intensity running program also demonstrated improvements in triglycerides.

Conclusion

In healthy active individuals, a physical activity program of at least 30 min in duration for three sessions/per week is associated with consistent improvements in health status.     

Weight Perception and Dietary Intake among Chinese Youth, 2004–2009

Background

Little is known on the extent of weight misperception and its relation with dietary intake among Chinese youth.

Purpose

The study aimed to investigate extent and correlates of weight misperception and its relation with dietary intake among Chinese youth.

Method

Data pertaining to Chinese youth, 6–17 years of age, from the 2004–2009 China Health and Nutrition Survey (N?=?3,923) were analyzed using STATA version 12.1. The heights and weights of the participants were measured by well-trained health workers at the participants' homes or a local clinic following the reference protocol recommended by the World Health Organization. The dietary intake data of the participants were collected on three consecutive days at both the household and individual levels.

Results

Of the children 6–11 years of age, 18.9 % were underweight and 15.3 % were overweight. Among the children 12–17 years of age, 18.3 % were underweight and 8.1 % were overweight. Less than 60 % of Chinese youth accurately estimated their weight status. Nutrition knowledge was positively related to a perception of being overweight (adjusted odds ratio [AOR]?=?1.98, p?=?.007) among children 12–17 years of age. A perception of being overweight was positively associated with fat and protein intake among children 6–11 years of age (p?<?.05).

Conclusions

A discrepancy exists between the actual and perceived weight status of Chinese youth. Efforts are needed in China to promote accurate weight perception, healthy weight, and eating behaviors.     

The detection and measurement of interleukin-6 in venous and capillary blood samples,and in sweat collected at rest and during exercise

Purpose

This study aimed to quantify the relationship between venous and capillary blood sampling methods for the measurement of plasma interleukin-6 (IL-6). A parallel study was conducted to determine the possibility of measuring IL-6 in sweat using an enzyme-linked immunosorbent assay (ELISA) and investigate the relationship between plasma- and sweat-derived measures of IL-6.

Methods

Twelve male participants were recruited for the measurement of IL-6 at rest and during exercise (study 1). An additional group of five female participants was recruited for the measurement of IL-6 in venous blood versus sweat at rest and following exercise (study 2). In study 1, venous and capillary blood samples were collected at rest and in response to exercise. In study 2, venous and sweat samples were collected following exercise.

Results

Mean plasma IL-6 concentration was not different between venous and capillary blood sampling methods either at rest (4.27 ± 5.40 vs. 4.14 ± 4.45 pg ml^?1), during (5.40 ± 5.17 vs. 5.58 ± 6.34 pg ml^?1), or in response to exercise (6.95 ± 6.37 vs. 6.99 ± 6.74 pg ml^?1). There was no IL-6 detectable in sweat either at rest or following exercise.

Conclusion

There are no differences in the measurement of plasma IL-6 using either venous or capillary blood sampling methods. Capillary measurement represents a minimally invasive way of measuring IL-6 and detecting changes in IL-6, which are linked to fatigue and overtraining.     

Preoperative body mass index and physical function are associated with length of stay and facility discharge after total knee arthroplasty

Background

Hospital length of stay (LOS) and facility discharge are primary drivers of the cost of total knee arthroplasty (TKA). We sought to identify modifiable patient factors that were associated with increased LOS and facility discharge after TKA.

Heart rate variability during exertional heat stress: effects of heat production and treatment

Purpose

We assessed the efficacy of different treatments (i.e., treatment with ice water immersion vs. natural recovery) and the effect of exercise intensities (i.e., low vs. high) for restoring heart rate variability (HRV) indices during recovery from exertional heat stress (EHS).

Methods

Nine healthy adults (26 ± 3 years, 174.2 ± 3.8 cm, 74.6 ± 4.3 kg, 17.9 ± 2.8 % body fat, 57 ± 2 mL·kg·^?1 min^?1 peak oxygen uptake) completed four EHS sessions incorporating either walking (4.0–4.5 km·h^?1, 2 % incline) or jogging (~7.0 km·h^?1, 2 % incline) on a treadmill in a hot-dry environment (40 °C, 20–30 % relative humidity) while wearing a non-permeable rain poncho for a slow or fast rate of rectal temperature (T _re) increase, respectively. Upon reaching a T _re of 39.5 °C, participants recovered until T _re returned to 38 °C either passively or with whole-body immersion in 2 °C water. A comprehensive panel of 93 HRV measures were computed from the time, frequency, time–frequency, scale-invariant, entropy and non-linear domains.

Results

Exertional heat stress significantly affected 60/93 HRV measures analysed. Analyses during recovery demonstrated that there were no significant differences between HRV measures that had been influenced by EHS at the end of passive recovery vs. whole-body cooling treatment (p > 0.05). Nevertheless, the cooling treatment required statistically significantly less time to reduce T _re (p < 0.001).

Conclusions

While EHS has a marked effect on autonomic nervous system modulation and whole-body immersion in 2 °C water results in faster cooling, there were no observed differences in restoration of autonomic heart rate modulation as measured by HRV indices with whole-body cold-water immersion compared to passive recovery in thermoneutral conditions.     

Pain sensitivity is normalized after a repeated bout of eccentric exercise

Purpose

The purpose of this study was to investigate the effect of repeated bouts of eccentric exercise on the nociceptive withdrawal reflex (NWR) threshold, a measure of sensitivity in the spinal nociceptive system.

Methods

Sixteen healthy students (age 25.7 ± 0.6 years, BMI 24.8 ± 1 kg m^?2) participated in this randomized, controlled, crossover study. Two identical bouts of high-intensity eccentric exercises were performed on the tibialis anterior muscle 7 days apart. Control sessions involving no exercise were performed 4 weeks apart the exercise sessions. Pressure pain thresholds (PPT) and the NWR threshold were recorded before, immediately after, and 1 day after both bouts of exercise.

Results

Pressure pain thresholds decreased significantly at two of the muscle belly sites on the day after initial bout compared with baseline. NWR threshold decreased by 25 ± 4 % immediately after initial bout and by 30 ± 5 % the next day (p < 0.05) as an indication of generalized pain hypersensitivity. On the contrary, no changes were found in both pain thresholds after second bout of eccentric exercise indicating that both localized and generalized pain sensitivity were normalized.

Conclusion

In conclusion, this study for the first time documented that an initial bout of unaccustomed high-intensity eccentric exercise, which results in muscle soreness can induce central sensitization. A repeated bout of exercise, however, facilitates inherent protective spinal mechanisms against the development of muscle soreness.     

Urinary trypsin inhibitor suppresses excessive generation of superoxide anion radical, systemic inflammation, oxidative stress, and endothelial injury in endotoxemic rats

Objective and design

The protective effects of ulinastatin, a human urinary trypsin inhibitor (UTI), against superoxide radical (O ₂ ^?· ) generation, systemic inflammation, lipid peroxidation, and endothelial injury were investigated in endotoxemic rats.

Materials and treatment

Twenty-one Wistar rats were allocated to a control group, a UTI group, and a sham group. A bolus of lipopolysaccharide (LPS; 3 μg/g) was administered intravenously to the control group, a bolus of LPS and UTI (5 U/g) to the UTI group, and a bolus of saline to the sham group.

Methods

The O ₂ ^?· generated was measured as the current in the right atrium using an electrochemical O ₂ ^?· sensor. Plasma nitrite, high mobility group box 1 (HMGB1), tumor necrosis factor (TNF)-α, inteleukin (IL)-6, malondialdehyde, and soluble intercellular adhesion molecule-1 (sICAM-1) were measured 360 min after LPS administration.

Results

The O ₂ ^?· current increased in the control group and was significantly attenuated in the UTI group after 55 min (P < 0.05 at 55–60 min, P < 0.01 at 65–360 min). Plasma nitrite, HMGB1, TNF-α, IL-6, malondialdehyde, and sICAM-1 were attenuated in the UTI group.

Conclusions

UTI suppressed excessive O ₂ ^?· generation, systemic inflammation, lipid peroxidation, and endothelial injury in endotoxemic rats.     

The influence of aerobic fitness on the recovery of peak power output

Purpose

The aims of this study were to evaluate the recovery kinetics of peak power output (PPO) following a maximal sprint, and to evaluate the influence of aerobic fitness on that recovery process.

Methods

On separate occasions, 16 well-trained men (age: 21 ± 3 years; height: 1.84 ± 0.05 m; and body mass: 78.8 ± 7.8 kg) performed a 30 s maximal sprint on a cycle ergometer, followed by a predetermined stationary rest period (5, 10, 20, 40, 80, and 160 s) and a subsequent 5 s sprint to determine PPO recovery kinetics. On another occasion, \({\dot V}{{\rm O}_{2}}\) was monitored during recovery from a 30 s sprint to provide a comparison with the recovery of PPO. Finally, subjects completed a \({\dot V}{{\rm O}_{2{\rm max}}}\) test to evaluate the influence of aerobic fitness on the recovery of PPO.

Results

Despite following similar time courses (F = 0.36, p = 0.558), and being well described by double-exponential models, the kinetic parameters of PPO and \({\dot V}{{\rm O}_{2}}\) in recovery were significantly different (p < 0.05). There was no significant relationship (r = 0.15; p = 0.578) between \({\dot V}{\rm O}_{2{\rm max}}\) and the time to achieve 50 % recovery of PPO. Moreover, there was no difference (p = 0.61) between the recovery kinetics of participants classified according to their \({\dot V}{\rm O}_{2{\rm max}}\) (59.4 ± 1.3 vs 48.5 ± 2.2 ml·kg^?1·min^?1).

Conclusion

Despite similar overall recovery kinetics, \({\dot V}{{\rm O}_{2}}\) and PPO show differences in key model parameters. Moreover, the recovery of PPO does not appear to be affected by aerobic fitness.     

Influence of the world’s most challenging mountain ultra-marathon on energy cost and running mechanics

Purpose

To examine the effects of the world’s most challenging mountain ultra-marathon (Tor des Géants^® 2012) on the energy cost of three types of locomotion (cycling, level and uphill running) and running kinematics.

Methods

Before (pre-) and immediately after (post-) the competition, a group of ten male experienced ultra-marathon runners performed in random order three submaximal 4-min exercise trials: cycling at a power of 1.5 W kg^?1 body mass; level running at 9 km h^?1 and uphill running at 6 km h^?1 at an inclination of +15 % on a motorized treadmill. Two video cameras recorded running mechanics at different sampling rates.

Results

Between pre- and post-, the uphill-running energy cost decreased by 13.8 % (P = 0.004); no change was noted in the energy cost of level running or cycling (NS). There was an increase in contact time (+10.3 %, P = 0.019) and duty factor (+8.1 %, P = 0.001) and a decrease in swing time (?6.4 %, P = 0.008) in the uphill-running condition.

Conclusion

After this extreme mountain ultra-marathon, the subjects modified only their uphill-running patterns for a more economical step mechanics.     

Short-term high-intensity interval and continuous moderate-intensity training improve maximal aerobic power and diastolic filling during exercise

Purpose

This study examined the effects of short-term high-intensity interval training (HIT) and continuous moderate-intensity training (CMT) on cardiac function in young, healthy men.

Methods

Sixteen previously untrained men (mean age of 25.1 ± 4.1 years) were randomly assigned to HIT and CMT (n = 8 each) and assessed before and after six sessions over a 12-day training period. HIT consisted of 8–12 intervals of cycling for 60 s at 95–100 % of pre-training maximal aerobic power ( $\dot{V}$ O_2max), interspersed by 75 s of cycling at 10 % $\dot{V}$ O_2max. CMT involved 90–120 min of cycling at 65 % pre-training $\dot{V}$ O_2max. Left ventricular (LV) function was determined at rest and during submaximal exercise (heart rate ~105 bpm) using two-dimensional and Doppler echocardiography.

Results

Training resulted in increased calculated plasma volume (PV) in both groups, accompanied by improved $\dot{V}$ O_2max in HIT (HIT: from 39.5 ± 7.1 to 43.9 ± 5.5 mL kg^?1 min^?1; CMT: from 39.9 ± 5.9 to 41.7 ± 5.3 mL kg^?1 min^?1; P < 0.001). Resting LV function was not altered. However, increased exercise stroke volume (P = 0.02) and cardiac output (P = 0.02) were observed, secondary to increases in end-diastolic volume (P < 0.001). Numerous Doppler and speckle tracking indices of diastolic function were similarly enhanced during exercise in both training groups and were related to changes in PV.

Conclusion

Short-term HIT and CMT elicit rapid improvements in $\dot{V}$ O_2max and LV filling without global changes in cardiac performance at rest.