Effects of strength training on running economy

The objective of this study was to compare the effect of different strength training protocols added to endurance training on running economy (RE). Sixteen well-trained runners (27.4 +/- 4.4 years; 62.7 +/- 4.3 kg; 166.1 +/- 5.0 cm), were randomized into two groups: explosive strength training (EST) (n = 9) and heavy weight strength training (HWT) (n = 7) group. They performed the following tests before and after 4 weeks of training: 1) incremental treadmill test to exhaustion to determine of peak oxygen uptake and the velocity corresponding to 3.5 mM of blood lactate concentration; 2) submaximal constant-intensity test to determine RE; 3) maximal countermovement jump test and; 4) one repetition maximal strength test in leg press. After the training period, there was an improvement in RE only in the HWT group (HWT = 47.3 +/- 6.8 vs. 44.3 +/- 4.9 ml . kg (-1) . min (-1); EST = 46.4 +/- 4.1 vs. 45.5 +/- 4.1 ml . kg (-1) . min (-1)). In conclusion, a short period of traditional strength training can improve RE in well-trained runners, but this improvement can be dependent on the strength training characteristics. When comparing to explosive training performed in the same equipment, heavy weight training seems to be more efficient for the improvement of RE.     

Maximal strength training improves running economy in distance runners

PURPOSE: The present study investigated the effect of maximal strength training on running economy (RE) at 70% of maximal oxygen consumption [formula: see text] and time to exhaustion at maximal aerobic speed (MAS). Responses in one repetition maximum (1RM) and rate of force development (RFD) in half-squats, maximal oxygen consumption, RE, and time to exhaustion at MAS were examined. METHODS: Seventeen well-trained (nine male and eight female) runners were randomly assigned into either an intervention or a control group. The intervention group (four males and four females) performed half-squats, four sets of four repetitions maximum, three times per week for 8 wk, as a supplement to their normal endurance training. The control group continued their normal endurance training during the same period. RESULTS: The intervention manifested significant improvements in 1RM (33.2%), RFD (26.0%), RE (5.0%), and time to exhaustion at MAS (21.3%). No changes were found in [formula: see text] or body weight. The control group exhibited no changes from pre to post values in any of the parameters. CONCLUSION: Maximal strength training for 8 wk improved RE and increased time to exhaustion at MAS among well-trained, long-distance runners, without change in maximal oxygen uptake or body weight.     

Effects of a 30-min running performed daily after downhill running on recovery of muscle function and running economy

This study investigated the effects of a 30-min level running performed daily for 6 days after downhill running (DHR) on indicators of muscle damage and running economy (RE). Fifty men were placed into five groups – control (CON), 40%, 50%, 60% and 70% (10 subjects per group) – by matching the baseline maximal oxygen consumption () among the groups. Subjects in the 40%, 50%, 60% and 70% groups had a treadmill (0°) run for 30 min at 40%, 50%, 60% and 70% of the pre-determined , respectively, at 1–6 days after a bout of 30-min DHR at −15% (−8.5°). Maximal voluntary isometric strength of the knee extensors, muscle soreness, plasma creatine kinase and lactate dehydrogenase activities were measured before, immediately after and every day for 7 days after DHR. RE was assessed by oxygen consumption, minute ventilation, respiratory exchange ratio, lactate, heart rate and rating of perceived exertion during a 5-min level running at 85% performed before and at 2, 5 and 7 days after DHR. All muscle damage markers changed significantly (P < 0.05) after DHR without significant differences among the groups. The RE parameters showed a significant decrease in RE for 7 days after DHR, but no significant differences in the changes were evident among the groups. These results suggest that the daily running performed after DHR did not have any beneficial or adverse effects on recovery of muscle damage and RE regardless of the intensity.     

The effects of muscle damage on running economy in healthy males

Published information on aspects related to muscle damage and running economy is both limited and contradictory. To contribute to the current debate, we investigated the effects of an eccentric exercise session on selected muscle damage indices in relation to running economy using 10 (mean age 23 +/- 1 years) healthy male volunteers. The eccentric exercise session consisted of 120 (12 x 10) maximal voluntary repetitions by each randomly selected leg at the angular velocity of 1.05 rad . s (-1). Muscle damage (creatine kinase, delayed onset muscle soreness, range of movement, and eccentric, concentric and isometric [at 60 degrees and 110 degrees knee flexion] peak torque) and running economy (oxygen consumption, pulmonary ventilation, respiratory exchange ratio and breaths per minute during treadmill running at 133 and 200 m . min (-1)) indicators, were assessed pre-, 24-, 48-, 72- as well as 96-h after exercise. All muscle damage indicators revealed significant changes at almost all time-points of assessment compared to pre-exercise data (p < 0.05). However, none of the running economy parameters disclosed any significant change throughout the study (p > 0.05). It was concluded that changes in muscle damage and muscle performance as measured in this study are not reflected by concomitant alterations in running economy at submaximal intensities.     

Chronic stretching and running economy

Research demonstrates an inverse relationship between the range of motion of selected joint movements (flexibility) and running economy. Since stretching exercises have been shown to increase joint range of motion, stretching exercises may be contraindicated for endurance running performance. Hence, this study investigated the influence of a 10-week program of stretching exercises on the oxygen costs of a 10 min sub-maximal (approx. 70% peak VO(2)) treadmill run. Thirty-two (16 female, 16 male) physically active, treadmill accommodated, college students participated in the study. All participants maintained their current activity level, with half the participants (8 female, 8 male) adding a 40 min, 3 days per week session of thigh and calf muscle stretching exercises. After 10 weeks, the stretching group (STR) exhibited a significant (P<0.05) increase (3.1+/-2.2 cm) in the sit-and-reach, while the non-stretching group (CON) experienced no significant (P>0.05) change (0.0+/-0.4 cm). However, neither the STR nor the CON exhibited a significant (P>0.05) change in the O(2) cost for the submaximal run. It is concluded, therefore, that a chronic stretching program does not necessarily negatively influence running economy.     

The effect of repeated periods of speed endurance training on performance,running economy,and muscle adaptations

The effect of repeated intense training interventions was investigated in eight trained male runners (maximum oxygen uptake [VO ₂‐max]: 59.3±3.2 mL/kg/min, mean±SD) who performed 10 speed endurance training (SET ; repeated 30‐seconds “all‐out” bouts) and 10 aerobic moderate‐intensity training sessions during two 40‐day periods (P1 and P2) separated by ~80 days of habitual training. Before and after both P1 and P2, subjects completed an incremental test to exhaustion to determine VO ₂‐max and a repeated running test at 90% vVO ₂‐max to exhaustion (RRT ) to determine short‐term endurance capacity. In addition, running economy (RE ) was measured at 60% vVO ₂‐max (11.9±0.5 km/h) and v10‐km (14.3±0.9 km/h), a 10‐km track‐running test was performed, and a biopsy from m. vastus lateralis was collected. 10‐km performance and VO ₂‐max (mL/min) were the same prior to P1 and P2, whereas RE was better (P <.05) before P2 than before P1. During P1 and P2, 10‐km performance (2.9% and 2.3%), VO ₂‐max (2.1% and 2.6%), and RE (1.9% and 1.8% at 60% vVO ₂‐max; 1.6% and 2.0% at v10‐km) improved (P <.05) to the same extent, respectively. Performance in RRT was 20% better (P <.05) after compared to before P2, with no change in P1. No changes in muscle expression of Na⁺,K⁺‐ATP ase α1, α2 and β1, NHE 1, SERCA 1 and SERCA 2, actin, and CaMKII were found during neither P1 nor P2. Thus, the present study demonstrates that a second period of intense training leads to improved short‐term performance and further improved RE , whereas 10‐km performance and VO ₂‐max improve to the same extent as during the first period.     

Relationship among maximum hip isometric strength,hip kinematics,and peak gluteal muscle force during running

ObjectiveTo determine if there is a relationship among isometric hip strength, hip kinematics, and peak gluteal muscle forces in cross-country runners during running.DesignCross Sectional.SettingUniversity Biomechanics Laboratory.ParticipantsForty-six NCAA Division III collegiate cross-country runners (18 males, 28 females).Main outcome measuresPearson correlation coefficients were used to describe relationships among isometric hip strength, hip kinematics, and peak gluteal muscle forces during the stance phase of running. Strength of correlations were interpreted as little to no relationship (r < 0.25), fair relationship (0.25 ≤ r < 0.5), moderate relationship (0.5 ≤ r < 0.75), and strong relationship (r ≥ 0.75). Correlations were considered significant if p < 0.05.ResultsLittle to no relationships were found among isometric hip strength and gluteal muscle forces during running (r < 0.25). A fair relationship was present between prone external rotation isometric hip strength and peak hip adduction (0.25 < r < 0.5). Little to no relationship was shown between gluteus medius force and hip internal rotation. Moderate relationships were present among peak gluteus medius and minimus muscle forces and peak hip adduction (0.5 < r < 0.75).ConclusionIsometric hip strength does not appear to be related to gluteal muscle forces and hip kinematics during the stance phase of running while gluteal muscle force was moderately related to hip adduction. Factors other than strength may be related to muscle force production and hip kinematics during running.     

Factors affecting running economy

Running economy, defined as the steady-state VO2 for a given running velocity, has been shown to account for a large and significant proportion of variation in distance-running performance among runners roughly comparable in VO2 max. Despite this recognition, relatively little is known regarding the potpourri of physiological, environmental, structural and mechanical factors potentially associated with a lower aerobic demand of running. Early attempts at quantifying the energy expenditure of exhaustive runs incorporated measurements of oxygen consumption before, during, and after exercise. The validity of this approach has been questioned, however, since recent evidence has demonstrated that only a moderate relationship exists between postexercise VO2 and anaerobic metabolism. The energy demands for submaximal running (i.e. running economy) can be quantified by calculating the steady-state VO2, expressed with respect to body mass and time, for a standardised, submaximal running speed. Since this variable represents the aerobic demand of running, the generation of energy must derive wholly from cell respiration and not from substantial protein catabolism. Research has indicated that at low to moderate work rates, the steady-state energy condition is attained in about 3 minutes. Trained individuals reach steady-state sooner than unfit subjects. While limited by methodological constraints, the existence of a steady-state has also been verified by the lack of blood lactate accumulation and the presence of a respiratory exchange ratio of less than 1.00. The ability of economy, either singly or in combination with VO2 max, to account for a substantial portion of performance variation among trained distance runners and untrained subjects of comparable ability and fitness level has been demonstrated in recent cross-sectional studies. Limited data from short and long term longitudinal research also suggests that endurance running success is linked to training and growth-related improvements in economy. Intraindividual variation in economy has been shown to vary between 2% and 11% for a given speed. Most of this variation can probably be attributed to biological error. While the majority of evidence does not support a gender difference in running economy, data from some studies suggest that males may be more economical than women. Prepubescent children are less economical than older children and adults, whereas older adults exhibit the same trend when compared to younger counterparts. Because of air and wind resistance, the aerobic demands of indoor treadmill running significantly underestimate the cost of overground running, especially at higher speeds.(ABSTRACT TRUNCATED AT 400 WORDS)     

Psychological state and running economy.

The primary purpose of the present review was to critique studies that examined the influence of psychological state (i.e., affect, perception, and cognition) on running economy (RE). However, only six studies included measures of oxygen consumption at a given workload (i.e., economy) and used running as the mode of exercise. Two of the six studies indicated that increased tension was highly correlated (r = 0.81) with increased oxygen cost and that reductions in tension, using stress management techniques, improved RE. Because of the sparsity of studies in this area, a secondary purpose of this review was to examine the influence of psychological state on the physiological and behavioral response to varying modes of exercise. Affect, induced through hypnosis and imagery, was effective in changing the response to exercise (i.e., heart rate, performance). Altered perception through the use of hypnosis or through personality characteristics did not alter the physiological response to exercise, perhaps because of the passive role of the exerciser in these situations. Lastly, cognition (i.e., mental strategy, coping, and biofeedback) elicited changes in the physiological and behavioral responses to exercise. Despite these physiological alterations, there were not changes in oxygen consumption in the majority of the studies. It is possible that changes in selected physiological responses (i.e., respiratory frequency) may be altered (e.g., biofeedback) without changes in oxygen consumption because of accommodation in other areas of the body (i.e., a-VO2 difference). Changes in economy possibly occur when these accommodation effects are overridden by the physiological adaptations resulting from longer training periods. In conclusion, psychological state can influence the physiological and behavioral response to exercise. Furthermore, this review supports the use of a multidisciplinary approach to examine the interactional effects of physiology, biomechanics, psychology, and neurophysiology to adequately determine mechanisms underlying changes in RE.     

Physiological, anthropometric, and training correlates of running economy.

Potential physiological, anthropometric, and training determinants of running economy (RE) were studied in a heterogeneous group of habitual distance runners (N = 188, 119 males, 69 females). RE was measured as VO2 (ml.kg-1.min-1) during level treadmill running at 161 m.min-1 (6 mph) (VO2-6). Examined as potential determinants of RE were heart rate and ventilation while running at 6 mph (HR6, VE6), VO2max (ml.kg-1 x min-1), % fat, age, gender, height, weight, estimated leg mass, typical training pace, training volume, and sit-and-reach test performance. RE was entered as the dependent variable and the potential determinants as independent variables in zero-order correlation and multiple regression analyses. Zero-order correlation analysis found VO2max, HR6, and VE6 to be significantly, positively correlated with VO2-6 (P < 0.001). Multiple regression analysis, in which the independent effect of each predictor variable was examined, revealed VO2-6 to be positively correlated with VO2max (P < 0.001), HR6 (P < 0.001), VE6 (P < 0.001), and age (P < 0.05) and negatively correlated with weight (P < 0.01). These findings indicate that, in a diverse group of runners, better RE (VO2-6) is associated with lower VO2max, lower submaximal exercise VE and HR, lower age, and greater weight.     

Biomechanical factors affecting running economy

PURPOSE: The present study was designed to investigate kinematics, kinetics, and muscle activity for explaining running economy at different running speeds. METHODS: A total of 17 young endurance runners ran at 12-13 different running speeds. Respiratory gases were collected. Kinematic records were obtained by a high-speed video camera, and 3-D ground reaction forces (GRF) were measured simultaneously with telemetric EMG recordings of the selected leg muscles. In the analysis, joint moments and power were calculated by inverse dynamic methods. RESULTS: The oxygen consumption and energy expenditure increased quite linearly with increasing running speed. However, already at the slowest speed, interindividual differences in running economy were noticed, and they increased with increasing running speed. Simultaneously, the instantaneous joint moment-angular velocity curves of the ankle and knee joints shifted to the right and upward, thus increasing joint power in the push-off phase of contact. Most definitive was the increase in EMG-activity of the BF muscle and its correlation with energy expenditure (r = 0.48, P < 0.05). This two-joint muscle seems to be very active during the maximal running: its amplitude increased (P < 0.05) both in the swinging and contact phases with increasing running speed. CONCLUSIONS: The increased EMG of working muscles and the associated increase in power output may partly explain the increased energy expenditure with increasing running speed. Lower performances in running economy by some of the athletes may also be explained by poor running technique, such as unusually high braking and mediolateral forces, which may be caused by limited action of the hamstring muscles. However, no exclusive biomechanical parameters could be identified to explain the running economy.     

Effects of concurrent endurance and strength training on running economy and .VO(2) kinetics

PURPOSE: It has been suggested that endurance training influences the running economy (CR) and the oxygen uptake (.VO(2)) kinetics in heavy exercise by accelerating the primary phase and attenuating the .VO(2) slow component. However, the effects of heavy weight training (HWT) in combination with endurance training remain unclear. The purpose of this study was to examine the influence of a concurrent HWT+endurance training on CR and the .VO(2) kinetics in endurance athletes. METHODS: Fifteen triathletes were assigned to endurance+strength (ES) or endurance-only (E) training for 14 wk. The training program was similar, except ES performed two HWT sessions a week. Before and after the training period, the subjects performed 1) an incremental field running test for determination of .VO(2max) and the velocity associated (V(.VO2max)), the second ventilatory threshold (VT(2)); 2) a 3000-m run at constant velocity, calculated to require 25% of the difference between .VO(2max) and VT(2), to determine CR and the characteristics of the VO(2) kinetics; 3) maximal hopping tests to determine maximal mechanical power and lower-limb stiffness; 4) maximal concentric lower-limb strength measurements. RESULTS: After the training period, maximal strength were increased (P < 0.01) in ES but remained unchanged in E. Hopping power decreased in E (P < 0.05). After training, economy (P < 0.05) and hopping power (P < 0.001) were greater in ES than in E. .VO(2max), leg hopping stiffness and the .VO(2) kinetics were not significantly affected by training either in ES or E. CONCLUSION: Additional HWT led to improved maximal strength and running economy with no significant effects on the .VO(2) kinetics pattern in heavy exercise.     

Effects of cycle strategy and fibre composition on muscle glycogen depletion pattern and subsequent running economy

PURPOSE: In this study, the effects of variable and constant-intensity cycling on muscle glycogen depletion patterns and subsequent running economy was examined. 60 minutes of cycling at a constant power (CON) or variable intensity (VAR) followed by a treadmill run to determine running economy was completed by nine male triathletes (Vo(2)max = 67.7 (4.9 ml) kg(-) min(-1)). During CON, there was greater glycogen depletion in the type I fibres compared with type II (0.08 (0.04) vs 0.02 (0.01) optical density (OD) units; p<0.05), while during VAR, there was greater glycogen depletion in the type II fibres compared with type I (0.06 (0.03) vs 0.03 (0.02) OD; p<0.05). The variation in muscle glycogen depletion patterns was not associated with the detriment in running economy, which was not significantly different between conditions (52.1 vs 52.8 ml kg(-1) min(-1)). There was a strong correlation between total muscle glycogen depletion and the change in running Vo(2) (r = 0.73, p<0.05) when the data from both trials were combined. There was also a negative correlation between type I fibre percentage and glycogen depletion within type II fibres during CON (r = -0.85, p<0.05). The results demonstrate that the decrease in running economy, subsequent to 60 minutes of cycling, is not affected by the cycling strategy employed. While different glycogen depletion patterns in the type I and II fibres were observed between conditions, total glycogen depletion may be more important to subsequent running economy. The percentage of type I fibres was associated with the glycogen depletion pattern during constant load, but not variable-intensity exercise.     

The effects of a downhill running bout on running economy

This study investigated whether downhill (DH) running (10-min @ 214.4 m·min(-1) and -10% grade) would elicit acute and delayed effects on running economy (RE) upon completion of DH running (RE2) and daily over 72 h (RE3, RE4, RE5). Fifteen runners (8 female, 7 male) completed the protocol. RE was measured during level running performed at 70% VO2peak. A baseline RE test (RE1) was used for comparison. Muscle soreness was significantly elevated at RE3 and RE4 vs. RE1. Oxygen uptake was significantly elevated at RE2 relative to RE3, RE4 and RE5 but was not different from RE1. Heart rate was similarly elevated at RE2. Measures of ankle, knee and hip joint angles at heel strike and toe off were not affected at any time-point in a subset of subjects (N = 6). A short DH running bout did not elicit significant delayed adverse effects on oxygen uptake or gait parameters relative to baseline.     

Leg heating and cooling influences running stride parameters but not running economy

To evaluate the effect of temperature on running economy (RE) and stride parameters in 10 trained male runners (VO2peak 60.8 +/- 6.8 ml . kg (-1) . min (-1)), we used water immersion as a passive temperature manipulation to contrast localised pre-heating, pre-cooling, and thermoneutral interventions prior to running. Runners completed three 10-min treadmill runs at 70 % VO2peak following 40 min of randomised leg immersion in water at 21.0 degrees C (cold), 34.6 degrees C (thermoneutral), or 41.8 degrees C (hot). Treadmill runs were separated by 7 days. External respiratory gas exchange was measured for 30 s before and throughout the exercise and stride parameters were determined from video analysis in the sagittal plane. RE was not affected by prior heating or cooling with no difference in oxygen cost or energy expenditure between the temperature interventions (average VO2 3rd-10th min of exercise: C, 41.6 +/- 3.4 ml . kg (-1) . min (-1); TN, 41.6 +/- 3.0; H, 41.8 +/- 3.5; p = 0.94). Exercise heart rate was affected by temperature (H > TN > C; p < 0.001). During minutes 3 - 5 of running the respiratory-exchange and minute ventilation/oxygen consumption ratios were greater in cold compared with thermoneutral (p < 0.05). Averaged over the full 10 min of exercise, stride length was shorter and stride frequency higher for the C trial compared to TN and H (p < 0.01). Leg temperature manipulation did not influence running economy despite changes in stride parameters that might indicate restricted muscle-tendon elasticity after pre-cooling. Larger changes in stride mechanics than those produced by the current temperature intervention are required to influence running economy.     

A physiologist's view of running economy

The relationship between VO2 and velocity of running (running economy) has been rather casually dealt with until very recently, and there still remains considerable disagreement as to the importance of this variable. Various factors which have been shown, or appear, to affect running economy include environment (temperature, altitude, running surface), fatigue, age, weight, state of fitness, and inherent differences. That differences between individuals and within individuals can and do exist seems clear; the questions which need to be addressed in future research are: (1) What type of training is most effective in bringing about changes in running economy? and (2) How much change in economy can be expected with optimum training? Furthermore, it is suggested that running economy be investigated as an entity, so that changes that may take place with time or training can be more accurately related to their cause.