Philo U. Saunders

Factors Affecting Running Economy in Trained Distance Runners

Running economy (RE) is typically defined as the energy demand for a given velocity of submaximal running, and is determined by measuring the steady-state consumption of oxygen (V̇O2) and the respiratory exchange ratio. Taking body mass (BM) into consideration, runners with good RE use less energy and therefore less oxygen than runners with poor RE at the same velocity. There is a strong association between RE and distance running performance, with RE being a better predictor of performance than maximal oxygen uptake (V̇O2max) in elite runners who have a similar V̇O2max.RE is traditionally measured by running on a treadmill in standard laboratory conditions, and, although this is not the same as overground running, it gives a good indication of how economical a runner is and how RE changes over time. In order to determine whether changes in RE are real or not, careful standardisation of footwear, time of test and nutritional status are required to limit typical error of measurement. Under controlled conditions, RE is a stable test capable of detecting relatively small changes elicited by training or other interventions. When tracking RE between or within groups it is important to account for BM. As V̇O2 during submaximal exercise does not, in general, increase linearly with BM, reporting RE with respect to the 0.75 power of BM has been recommended.A number of physiological and biomechanical factors appear to influence RE in highly trained or elite runners. These include metabolic adaptations within the muscle such as increased mitochondria and oxidative enzymes, the ability of the muscles to store and release elastic energy by increasing the stiffness of the muscles, and more efficient mechanics leading to less energy wasted on braking forces and excessive vertical oscillation.Interventions to improve RE are constantly sought after by athletes, coaches and sport scientists. Two interventions that have received recent widespread attention are strength training and altitude training. Strength training allows the muscles to utilise more elastic energy and reduce the amount of energy wasted in braking forces. Altitude exposure enhances discrete metabolic aspects of skeletal muscle, which facilitate more efficient use of oxygen.The importance of RE to successful distance running is well established, and future research should focus on identifying methods to improve RE. Interventions that are easily incorporated into an athlete’s training are desirable.

Running in a minimalist and lightweight shoe is not the same as running barefoot: a biomechanical study

Aim The purpose of this study was to determine the changes in running mechanics that occur when highly trained runners run barefoot and in a minimalist shoe, and specifically if running in a minimalist shoe replicates barefoot running. Methods Ground reaction force data and kinematics were collected from 22 highly trained runners during overground running while barefoot and in three shod conditions (minimalist shoe, racing flat and the athletes regular shoe). Three-dimensional net joint moments and subsequent net powers and work were computed using Newton-Euler inverse dynamics. Joint kinematic and kinetic variables were statistically compared between barefoot and shod conditions using a multivariate analysis of variance for repeated measures and standardised mean differences calculated. Results There were significant differences between barefoot and shod conditions for kinematic and kinetic variables at the knee and ankle, with no differences between shod conditions. Barefoot running demonstrated less knee flexion during midstance, an 11% decrease in the peak internal knee extension and abduction moments and a 24% decrease in negative work done at the knee compared with shod conditions. The ankle demonstrated less dorsiflexion at initial contact, a 14% increase in peak power generation and a 19% increase in the positive work done during barefoot running compared with shod conditions. Conclusions Barefoot running was different to all shod conditions. Barefoot running changes the amount of work done at the knee and ankle joints and this may have therapeutic and performance implications for runners.

Short-term plyometric training improves running economy in highly trained middle and long distance runners.

Fifteen highly trained distance runners (&OV0312;O2max 71.1 ± 6.0 ml·min−1·kg−1, mean ± SD) were randomly assigned to a plyometric training (PLY; n = 7) or control (CON; n = 8) group. In addition to their normal training, the PLY group undertook 3 × 30 minutes PLY sessions per week for 9 weeks. Running economy (RE) was assessed during 3 × 4 minute treadmill runs (14, 16, and 18 km·h−1), followed by an incremental test to measure &OV0312;O2max. Muscle power characteristics were assessed on a portable, unidirectional ground reaction force plate. Compared with CON, PLY improved RE at 18 km·h−1 (4.1%, p = 0.02), but not at 14 or 16 km·h−1. This was accompanied by trends for increased average power during a 5-jump plyometric test (15%, p = 0.11), a shorter time to reach maximal dynamic strength during a strength quality assessment test (14%, p = 0.09), and a lower &OV0312;O2-speed slope (14%, p = 0.12) after 9 weeks of PLY. There were no significant differences in cardiorespiratory measures or &OV0312;O2max as a result of PLY. In a group of highly-trained distance runners, 9 weeks of PLY improved RE, with likely mechanisms residing in the muscle, or alternatively by improving running mechanics.

Oral administration of the probiotic Lactobacillus fermentum VRI-003 and mucosal immunity in endurance athletes

Objective To evaluate the ability of a probiotic Lactobacillus fermentum VRI-003 (PCC) to enhance the mucosal immune system of elite athletes. Design and setting A double-blind, placebo-controlled, crossover trial was conducted over a 4-month period of winter training. Participants 20 healthy elite male distance runners. Interventions PCC was given at a daily dose of 1.26×1010 as a freeze-dried powder in gelatin capsules. Placebo capsules contained an inert excipient. Main outcome measures Treadmill performance (monthly), mucosal and systemic immunity (monthly), training (daily) and illness (daily) were assessed. Serum cytokine levels, salivary IgA levels and incidence, duration and severity of respiratory tract infections were measured. Results Subjects reported less than half the number of days of respiratory symptoms during PCC treatment (30 days) compared with placebo (72 days, p<0.001). Illness severity was also lower for episodes occurring during the PCC treatment (p = 0.06). There were no significant differences in the mean change in salivary IgA and IgA1 levels, or in interleukin (IL)4 and IL12 levels, between treatments. However, PCC treatment elicited a twofold (p = 0.07) greater change in whole-blood culture interferon gamma (IFNγ) compared with placebo. No substantial changes in running performance measures were seen over the study period. Conclusions Prophylactic administration of PCC was associated with a substantial reduction in the number of days and severity of respiratory illness in a cohort of highly trained distance runners. Maintenance of IFNγ levels may be one mechanism underpinning the positive clinical outcomes.

Relationships Between Repeated Sprint Testing, Speed, and Endurance

Pyne, DB, Saunders, PU, Montgomery, PG, Hewitt, AJ, and Sheehan, K. Relationships between repeated sprint testing, speed, and endurance. J Strength Cond Res 22(5): 1633-1637, 2008-Repeated sprint testing is gaining popularity in team sports, but the methods of data analysis and relationships to speed and endurance qualities are not well described. We compared three different methods for analyzing repeated sprint test results, and we quantified relationships between repeated sprints, short sprints, and endurance test scores. Well-trained male junior Australian Football players (n = 60, age 18.1 ± 0.4 years, height 1.88 ± 0.07 m, mass 82.0 ± 8.1 kg; mean ± SD) completed a 6 × 30-m repeated sprint running test on a 20-second cycle, a 20-m sprint test (short sprint), and the 20-m multistage shuttle run for endurance. Repeated sprint results were evaluated in three ways: total time for all six sprints (TOTAL), percent change from predicted times (PRED) from the fastest 30-m sprint time, and percent change from first to last sprint (CHANGE). We observed a very large decrement (CHANGE 6.3 ± 0.7%, mean ± 90% confidence limits) in 30-m performance from the first to last sprint (4.16 ± 0.10 to 4.42 ± 0.11 seconds, mean ± SD). Results from TOTAL were highly correlated with 20-m sprint and 20-m multistage shuttle run tests. Performance decrements calculated by PRED were highly correlated with TOTAL (r = 0.91), but neither method was directly comparable with CHANGE (r = −0.23 and r = 0.12 respectively). TOTAL was moderately correlated with fastest 20-m sprint time (r = 0.66) but not the 20-m multistage shuttle run (r = −0.20). Evaluation of repeated sprint testing is sensitive to the method of data analysis employed. The total sprint time and indices of the relative decrement in performance are not directly interchangeable. Repeated sprint ability seems more related to short sprint qualities than endurance fitness.

Reproducibility of performance changes to simulated live high/train low altitude.

UNLABELLED Elite athletes often undertake multiple altitude exposures within and between training years in an attempt to improve sea level performance. PURPOSE To quantify the reproducibility of responses to live high/train low (LHTL) altitude exposure in the same group of athletes. METHODS Sixteen highly trained runners with maximal aerobic power (VO2max) of 73.1 +/- 4.6 and 64.4 +/- 3.2 mL x kg(-1) x min(-1) (mean +/- SD) for males and females, respectively, completed 2 x 3-wk blocks of simulated LHTL (14 h x d(-1), 3000 m) or resided near sea level (600 m) in a controlled study design. Changes in the 4.5-km time trial performance and physiological measures including VO2max, running economy and hemoglobin mass (Hb(mass)) were assessed. RESULTS Time trial performance showed small and variable changes after each 3-wk altitude block in both the LHTL (mean [+/-90% confidence limits]: -1.4% [+/-1.1%] and 0.7% [+/-1.3%]) and the control (0.5% [+/-1.5%] and -0.7% [+/-0.8%]) groups. The LHTL group demonstrated reproducible improvements in VO2max (2.1% [+/-2.1%] and 2.1% [+/-3.9%]) and Hb(mass) (2.8% [+/-2.1%] and 2.7% [+/-1.8%]) after each 3-wk block. Compared with those in the control group, the runners in the LHTL group were substantially faster after the first 3-wk block (LHTL - control = -1.9% [+/-1.8%]) and had substantially higher Hb(mass) after the second 3-wk block (4.2% [+/-2.1%]). There was no substantial difference in the change in mean VO2max between the groups after the first (1.2% [+/-3.3%]) or second 3-wk block (1.4% [+/-4.6%]). CONCLUSIONS Three-week LHTL altitude exposure can induce reproducible mean improvements in VO2max and Hb(mass) in highly trained runners, but changes in time trial performance seem to be more variable. Competitive performance is dependent not only on improvements in physiological capacities that underpin performance but also on a complex interaction of many factors including fitness, fatigue, and motivation.

Altitude training and haemoglobin mass from the optimised carbon monoxide rebreathing method determined by a meta-analysis

Objective To characterise the time course of changes in haemoglobin mass (Hbmass) in response to altitude exposure. Methods This meta-analysis uses raw data from 17 studies that used carbon monoxide rebreathing to determine Hbmass prealtitude, during altitude and postaltitude. Seven studies were classic altitude training, eight were live high train low (LHTL) and two mixed classic and LHTL. Separate linear-mixed models were fitted to the data from the 17 studies and the resultant estimates of the effects of altitude used in a random effects meta-analysis to obtain an overall estimate of the effect of altitude, with separate analyses during altitude and postaltitude. In addition, within-subject differences from the prealtitude phase for altitude participant and all the data on control participants were used to estimate the analytical SD. The ‘true’ between-subject response to altitude was estimated from the within-subject differences on altitude participants, between the prealtitude and during-altitude phases, together with the estimated analytical SD. Results During-altitude Hbmass was estimated to increase by ∼1.1%/100 h for LHTL and classic altitude. Postaltitude Hbmass was estimated to be 3.3% higher than prealtitude values for up to 20 days. The within-subject SD was constant at ∼2% for up to 7 days between observations, indicative of analytical error. A 95% prediction interval for the ‘true’ response of an athlete exposed to 300 h of altitude was estimated to be 1.1–6%. Conclusions Camps as short as 2 weeks of classic and LHTL altitude will quite likely increase Hbmass and most athletes can expect benefit.

Influence of training loads on patterns of illness in elite distance runners

Objective:To investigate relationships between training mileage and intensity, and the type, incidence, severity, and duration of respiratory illness in distance runners, and the impact of illness on submaximal and maximal running performance. Design:A longitudinal observational study of distance runners with serial monitoring of training loads and clinical patterns of illness. Setting:A 4-month winter training period in the Southern Hemisphere. Participants:A total of 20 highly trained (elite) male middle-distance and distance runners competing at the national and international levels. Main Outcome Measures:Training was quantified by mileage (km), intensity (scale, 1-5), and load (volume × intensity). Symptoms and signs of respiratory illness (type, duration, and severity) were verified by a physician at a weekly review. Performance was monitored by measuring submaximal and maximal oxygen uptake and time to exhaustion on a incremental treadmill test. Results:A majority of subjects (15/20) experienced 1 or more episodes of respiratory illness (mean, 2.5 episodes; range, 1-5), with 79% of symptoms classified as upper respiratory in origin. There were no significant differences in mean weekly mileage (P = 0.43), training intensity (P = 0.85), or training load (P = 0.45) between healthy runners and those affected by illness. Mean weekly (88 ± 46 km) and mean monthly (373 ± 163 km) mileages prior to each episode of illness were similar to the overall study means (95.5 ± 36.4 km and 382 ± 146 km). There were no substantial relationships between mean weekly training mileage, intensity, or training load and the number of illnesses reported (all r < 0.20). Neither submaximal nor maximal running performance was significantly affected by the presence of illness. Conclusions:Differences in training mileage, intensity, and load were not associated with the incidence of respiratory illness in highly trained middle-distance and distance runners. Runners with mild illness can be reassured that symptoms will not necessarily impair submaximal and maximal performance.

ANTHROPOMETRIC AND STRENGTH CORRELATES OF FAST BOWLING SPEED IN JUNIOR AND SENIOR CRICKETERS

The aim of this study was to characterize relationships between anthropometric and isoinertial strength characteristics and bowling speed in junior and senior cricket fast bowlers. Subjects were first-class senior (n = 24; mean ± SD age = 23.9 ± 4.8 years, height = 187.4 ± 4.8 cm, mass = 87.8 ± 8.4 kg) and junior representative (n = 48; mean ± SD age = 14.8 ± 1.3 years, height = 175.7 ± 9.8 cm, mass = 65.8 ± 12.9 kg) male fast bowlers. A full anthropometric profile, upper-and lower-body isoinertial strength tests, and peak bowling speed (Vpeak) were assessed on the same day. The senior bowlers had a substantially faster Vpeak (126.7 km·h−1) than the juniors (99.6 km·h−1), a larger estimated muscle mass (seniors 40.0 ± 3.9 kg, juniors 28.3 ± 5.6 kg), and a greater bench press throw and deltoid throw (all p < 0.01). The best multiple predictors of Vpeak for the junior bowlers were the static jump, bench throw, body mass, percentage muscle mass, and height (multiple-correlation r = 0.86). For the senior bowlers, static jump and arm length correlated positively with Vpeak (multiple-correlation r = 0.74). The 1-legged countermovement jump was negatively correlated with Vpeak in both groups. We conclude that differences in Vpeak between junior and senior bowlers relate primarily to body mass and upper-body strength. However, lower body strength is a more important contributor to Vpeak in senior bowlers.

Preparation for football competition at moderate to high altitude

Analysis of ∼100 years of home‐and‐away South American World Cup matches illustrate that football competition at moderate/high altitude (>2000 m) favors the home team, although this is more than compensated by the likelihood of sea‐level teams winning at home against the same opponents who have descended from altitude. Nevertheless, the home team advantage at altitudes above ∼2000 m may reflect that traditionally, teams from sea level or low altitude have not spent 1–2 weeks acclimatizing at altitude. Despite large differences between individuals, in the first few days at high altitude (e.g. La Paz, 3600 m) some players experience symptoms of acute mountain sickness (AMS) such as headache and disrupted sleep, and their maximum aerobic power (VO2max) is ∼25% reduced while their ventilation, heart rate and blood lactate during submaximal exercise are elevated. Simulated altitude for a few weeks before competition at altitude can be used to attain partial ventilatory acclimation and ameliorated symptoms of AMS. The variety of simulated altitude exposures usually created with enriched nitrogen mixtures of air include resting or exercising for a few hours per day or sleeping ∼8 h/night in hypoxia. Preparation for competition at moderate/high altitude by training at altitude is probably superior to simulated exposure; however, the optimal duration at moderate/high altitude is unclear. Preparing for 1–2 weeks at moderate/high altitude is a reasonable compromise between the benefits associated with overcoming AMS and partial restoration of VO2max vs the likelihood of detraining.