The reliability of running economy among trained distance runners and field-based players

Test-Retest Reliability of Running Economy and Metabolic and Cardiorespiratory Parameters During a Multistage Incremental Treadmill Test in Male Middle- and Long-Distance Runners

This study investigated the test-retest reliability of running economy (RE) and metabolic and cardiorespiratory parameters related to endurance running performance using a multistage incremental treadmill test. On two occasions separated by 21-28 days, 12 male middle- and long-distance runners ran at 10, 11, 12, 13, and 14 km/hr for 8 min each stage, immediately followed by a ramp test to volitional exhaustion. Carbohydrate (10% maltodextrin solution) was consumed before and during the test to provide ∼1 g/min of exercise. RE, minute ventilation (V˙E), oxygen consumption (V˙O2), carbon dioxide production (V˙CO2), respiratory exchange ratio (RER), heart rate (HR), ratings of perceived exertion (RPE), and blood glucose and lactate concentrations were recorded for each stage and at volitional exhaustion. Time-to-exhaustion (TTE) and peak oxygen consumption (V˙O2peak) during the ramp test were also recorded. Absolute reliability, calculated as the coefficient of variation (CV) between repeated measures, ranged from 2.3% to 3.1% for RE, whereas relative reliability, calculated as the intraclass correlation coefficient (ICC), ranged from .42 to .79. V˙E, V˙O2, V˙O2peak, V˙CO2, RER, and HR had a CV of 1.1%-4.3% across all stages. TTE and RPE had a CV of 7.2% and 2.3%-10.8%, respectively, while glucose and lactate had a CV of 4.0%-17.8%. All other parameters, except for blood glucose, were demonstrated to have good-to-excellent relative reliability assessed by ICC. Measures of RE, V˙O2peak, and TTE were reliable during this two-phase multistage incremental treadmill test in a cohort of trained and highly trained male middle- and long-distance runners.

Reliability of Change-of-Direction Economy in Soccer Players

Purpose: To evaluate the reliability of new change-of-direction-economy tests (assessing energetic efficiency when performing continuous shuttle runs) compared with common running-economy tests in soccer players Methods: Sixteen subelite, male soccer players were recruited to perform a testing battery involving running economy (RE), 10-m shuttle-running economy (SRE10), and 20-m shuttle-running economy (SRE20) at 8.4 km·h−1 mean speed on 2 different days within 48 hours. SRE10 and SRE20 consisted of continuous shuttle runs interspersed with 180° directional changes. During the RE, SRE20, and SRE10 tests, respiratory exchange ratio and oxygen uptake were collected and used to calculate the movement-economy values over any running condition as oxygen cost and energetic cost. The secondary variables (carbon dioxide production, heart rate, minute ventilation, and blood lactate) were also monitored during all tests. Results: Depending on expression (oxygen cost or energetic cost), reliability was established for RE (CV: 5.5%–5.8%; ICC = .77–.88), SRE10 (CV: 3.5%–3.8%; ICC = .78–.96), and SRE20 (CV: 3.5%–3.8%; ICC = .66–.94). All secondary physiological variables reported good reliability (CV < 10%), except for blood lactate (CV < 35.8). The RE, SRE10, and SRE20 tests show good reliability in soccer players, whereas blood lactate has the highest variability among physiological variables during the economy tests. Conclusion: The assessment of change-of-direction economy through performing 20- and 10-m shuttle runs is reliable and can be applied to evaluate soccer players’ energetic movement efficiency under more soccer-specific running conditions.

Convergent validity and reliability of a novel repeated agility protocol in junior rugby league players

Background: Rugby league involves repeated, complex, change-of-direction movements, although there are no test protocols that specifically assesses these physical fitness profiles. Thus, the current study examined the convergent validity and reliability of a repeated Illinois Agility (RIA) protocol in adolescent Rugby League players. Methods: Twenty-two junior Rugby League players completed 4 sessions with each separated by 7 days. Initially, physical fitness characteristics at baseline (i.e., multi-stage fitness, countermovement jump, 30-m sprint, single-effort agility and repeated sprint ability [RSA]) were assessed. The second session involved a familiarisation of RIA and repeated T-agility test (RTT) protocols. During the third and fourth sessions, participants completed the RIA and RTT protocols in a randomised, counterbalanced design to examine the validity and test-retest reliability of these protocols. Results: For convergent validity, significant correlations were identified between RIA and RTT performances (r= >0.80; p<0.05). For contributors to RIA performance, significant correlations were identified between all baseline fitness characteristics and RIA (r = >0.71; p < 0.05). Reliability of the RIA protocol was near perfect with excellent intra-class correlation coefficient (0.87-0.97), good ratio limits of agreement (×/÷ 1.05-1.06) and low coefficient of variations (1.77-1.97%). Conclusions: The current study has demonstrated the RIA to be a simple, valid and reliable field test that can provide coaches with information about their athlete's ability to sustain high intensity, multi-directional running efforts.

Convergent validity and reliability of a novel repeated agility protocol in junior rugby league players

Background:: Rugby league involves repeated, complex, and high intensity change-of-direction (COD) movements with no existing test protocols that specifically assesses these multiple physical fitness components simultaneously. Thus, the current study examined the convergent validity of a repeated Illinois Agility (RIA) protocol with the repeated T-agility protocol, and the repeatability of the RIA protocol in adolescent Rugby League players. Furthermore, aerobic capacity and anaerobic and COD performance were assessed to determine whether these physical qualities were important contributors to the RIA protocol. Methods: Twenty-two junior Rugby League players completed 4 sessions with each separated by 7 days. Initially, physical fitness characteristics at baseline (i.e., Beep test,, countermovement jump, 30-m sprint, single-effort COD and repeated sprint ability [RSA]) were assessed. The second session involved a familiarisation of RIA and repeated T-agility test (RTT) protocols. During the third and fourth sessions, participants completed the RIA and RTT protocols in a randomised, counterbalanced design to examine the validity and test-retest reliability of these protocols. Results: For convergent validity, significant correlations were identified between RIA and RTT performances (r= >0.80; p<0.05). For contributors to RIA performance, significant correlations were identified between all baseline fitness characteristics and RIA (r = >0.71; p < 0.05). Reliability of the RIA protocol was near perfect with excellent intra-class correlation coefficient (0.87-0.97), good ratio limits of agreement (×/÷ 1.05-1.06) and low coefficient of variations (1.8-2.0%). Conclusions: The current study has demonstrated the RIA to be a simple, valid and reliable field test for RL athletes that can provide coaches with information about their team's ability to sustain high intensity, multi-directional running efforts.

Convergent validity and reliability of a novel repeated agility protocol in junior rugby league players

Background: : Rugby league involves repeated, complex, and high intensity change-of-direction (COD) movements with no existing test protocols that specifically assesses these multiple physical fitness components simultaneously. Thus, the current study examined the convergent validity of a repeated Illinois Agility (RIA) protocol with the repeated T-agility protocol, and the repeatability of the RIA protocol in adolescent Rugby League players. Furthermore, aerobic capacity and anaerobic and COD performance were assessed to determine whether these physical qualities were important contributors to the RIA protocol. Methods: Twenty-two junior Rugby League players completed 4 sessions with each separated by 7 days. Initially, physical fitness characteristics at baseline (i.e., Multi-stage Shuttle test, countermovement jump, 30-m sprint, single-effort COD and repeated sprint ability [RSA]) were assessed. The second session involved a familiarisation of RIA and repeated T-agility test (RTT) protocols. During the third and fourth sessions, participants completed the RIA and RTT protocols in a randomised, counterbalanced design to examine the validity and test-retest reliability of these protocols. Results: For convergent validity, significant correlations were identified between RIA and RTT performances (r= >0.80; p<0.05). For contributors to RIA performance, significant correlations were identified between all baseline fitness characteristics and RIA (r = >0.71; p < 0.05). Reliability of the RIA protocol was near perfect with excellent intra-class correlation coefficient (0.87-0.97), good ratio limits of agreement (×/÷ 1.05-1.06) and low coefficient of variations (1.8-2.0%). Conclusions: The current study has demonstrated the RIA to be a simple, valid and reliable field test for RL athletes that can provide coaches with information about their team's ability to sustain high intensity, multi-directional running efforts.

Training Considerations for Optimising Endurance Development: An Alternate Concurrent Training Perspective

Whilst the "acute hypothesis" was originally coined to describe the detrimental effects of concurrent training on strength development, similar physiological processes may occur when endurance training adaptations are compromised. There is a growing body of research indicating that typical resistance exercises impair neuromuscular function and endurance performance during periods of resistance training-induced muscle damage. Furthermore, recent evidence suggests that the attenuating effects of resistance training-induced muscle damage on endurance performance are influenced by exercise intensity, exercise mode, exercise sequence, recovery and contraction velocity of resistance training. By understanding the influence that training variables have on the level of resistance training-induced muscle damage and its subsequent attenuating effects on endurance performance, concurrent training programs could be prescribed in such a way that minimises fatigue between modes of training and optimises the quality of endurance training sessions. Therefore, this review will provide considerations for concurrent training prescription for endurance development based on scientific evidence. Furthermore, recommendations will be provided for future research by identifying training variables that may impact on endurance development as a result of concurrent training.

The Effect of a Resistance Training Session on Physiological and Thermoregulatory Measures of Sub-maximal Running Performance in the Heat in Heat-Acclimatized Men

BACKGROUND

The current study examined the acute effects of a lower body resistance training (RT) session on physiological and thermoregulatory measures during a sub-maximal running protocol in the heat in heat-acclimatized men. Ten resistance-untrained men (age 27.4 ± 4.1 years; height 1.78 ± 0.06 m; body mass 76.8 ± 9.9 kg; peak oxygen uptake 48.2 ± 7.0 mL kg^-1 min^-1) undertook a high-intensity RT session at six-repetition maximum. Indirect muscle damage markers (i.e., creatine kinase [CK], delayed-onset muscle soreness [DOMS], and countermovement jump [CMJ]) were collected prior to, immediately post and 24 and 48 h after the RT session. The sub-maximal running protocol was performed at 70% of the ventilatory threshold, which was conducted prior to and 24 and 48 h following the RT session to obtain physiological and thermoregulatory measures.

RESULTS

The RT session exhibited significant increases in DOMS (p < 0.05; effect size [ES]: 1.41-10.53), whilst reduced CMJ (p < 0.05; ES: - 0.79-1.41) for 48 h post-exercise. There were no differences in CK (p > 0.05), although increased with moderate to large ES (0.71-1.12) for 48 h post-exercise. The physiological cost of running was increased for up to 48 h post-exercise (p < 0.05) with moderate to large ES (0.50-0.84), although no differences were shown in thermoregulatory measures (p > 0.05) with small ES (0.33).

CONCLUSION

These results demonstrate that a RT session impairs sub-maximal running performance for several days post-exercise, although thermoregulatory measures are unperturbed despite elevated muscle damage indicators in heat-acclimatized, resistance untrained men. Accordingly, whilst a RT session may not increase susceptibility to heat-related injuries in heat-acclimatized men during sub-maximal running in the heat, endurance sessions should be undertaken with caution for at least 48 h post-exercise following the initial RT session in resistance untrained men.

Implications of Impaired Endurance Performance following Single Bouts of Resistance Training: An Alternate Concurrent Training Perspective

A single bout of resistance training induces residual fatigue, which may impair performance during subsequent endurance training if inadequate recovery is allowed. From a concurrent training standpoint, such carry-over effects of fatigue from a resistance training session may impair the quality of a subsequent endurance training session for several hours to days with inadequate recovery. The proposed mechanisms of this phenomenon include: (1) impaired neural recruitment patterns; (2) reduced movement efficiency due to alteration in kinematics during endurance exercise and increased energy expenditure; (3) increased muscle soreness; and (4) reduced muscle glycogen. If endurance training quality is consistently compromised during the course of a specific concurrent training program, optimal endurance development may be limited. Whilst the link between acute responses of training and subsequent training adaptation has not been fully established, there is some evidence suggesting that cumulative effects of fatigue may contribute to limiting optimal endurance development. Thus, the current review will (1) explore cross-sectional studies that have reported impaired endurance performance following a single, or multiple bouts, of resistance training; (2) identify the potential impact of fatigue on chronic endurance development; (3) describe the implications of fatigue on the quality of endurance training sessions during concurrent training, and (4) explain the mechanisms contributing to resistance training-induced attenuation on endurance performance from neurological, biomechanical and metabolic standpoints. Increasing the awareness of resistance training-induced fatigue may encourage coaches to consider modulating concurrent training variables (e.g., order of training mode, between-mode recovery period, training intensity, etc.) to limit the carry-over effects of fatigue from resistance to endurance training sessions.

The repeated bout effect of traditional resistance exercises on running performance across 3 bouts

This study investigated the repeated bout effect of 3 typical lower body resistance-training sessions on maximal and submaximal effort running performance. Twelve resistance-untrained men (age, 24 ± 4 years; height, 1.81 ± 0.10 m; body mass, 79.3 ± 10.9 kg; peak oxygen uptake, 48.2 ± 6.5 mL·kg^-1·min^-1; 6-repetition maximum squat, 71.7 ± 12.2 kg) undertook 3 bouts of resistance-training sessions at 6-repetitions maximum. Countermovement jump (CMJ), lower-body range of motion (ROM), muscle soreness, and creatine kinase (CK) were examined prior to and immediately, 24 h (T24), and 48 h (T48) after each resistance-training bout. Submaximal (i.e., below anaerobic threshold (AT)) and maximal (i.e., above AT) running performances were also conducted at T24 and T48. Most indirect muscle damage markers (i.e., CMJ, ROM, and muscle soreness) and submaximal running performance were significantly improved (P < 0.05; 1.9%) following the third resistance-training bout compared with the second bout. Whilst maximal running performance was also improved following the third bout (P < 0.05; 9.8%) compared with other bouts, the measures were still reduced by 12%-20% versus baseline. However, the increase in CK was attenuated following the second bout (P < 0.05) with no further protection following the third bout (P > 0.05). In conclusion, the initial bout induced the greatest change in CK; however, at least 2 bouts were required to produce protective effects on other indirect muscle damage markers and submaximal running performance measures. This suggests that submaximal running sessions should be avoided for at least 48 h after resistance training until the third bout, although a greater recovery period may be required for maximal running sessions.

A novel running mechanic's class changes kinematics but not running economy

A novel method of running technique instruction, Midstance to Midstance Running (MMR), was studied to determine how MMR affected kinematics and running economy (RE) of recreational runners. An experimental pre-post randomized groups design was used. Participants (n = 18) were recreational runners who ran at least 3 days a week and 5 km per run. All testing was performed on a treadmill at 2.8 m·s. The intervention group (n = 9) completed 8 weeks of instruction in MMR; the control group (n = 9) continued running without instruction. The MMR group showed significant decreases in stride length (SL) (p = 0.02) and maximum knee flexion velocity in stance (p = 0.01), and a significant increase in stride rate (SR) (p = 0.02) after 8 weeks. No significant changes were found in heart rate, rating of perceived exertion, or RE. Midstance to Midstance Running was effective in changing SR and SL, but was not effective in changing other kinematic variables such as foot contact position and maximum knee flexion during swing. Midstance to Midstance Running did not affect RE. Evidence suggests that MMR may be an appropriate instructional method for recreational runners trying to decrease SL and increase SR.

The Acute Effect of Concurrent Training on Running Performance Over 6 Days

PURPOSE

This study examined the effects of strength training on alternating days and endurance training on consecutive days on running performance for 6 days.

METHODS

Sixteen male and 8 female moderately trained individuals were evenly assigned into concurrent-training (CCT) and strength-training (ST) groups. The CCT group undertook strength training on alternating days combined with endurance training on consecutive days for 6 days. One week later, the CCT group conducted 3 consecutive days of endurance training only to determine whether fatigue would be induced with endurance training alone (CCT-Con). Endurance training was undertaken to induce endurance-training stimulus and to measure the cost of running (CR), rating of perceived exertion (RPE), and time to exhaustion (TTE). The ST group undertook 3 strength-training sessions on alternating days. Maximal voluntary contraction (MVC), rating of muscle soreness (RMS), and rating of muscle fatigue (RMF) were collected prior to each strength and endurance session.

RESULTS

For the CCT group, small differences were primarily found in CR and RPE (ES = 0.17-0.41). However, moderate-to-large reductions were found for TTE and MVC (ES = 0.65-2.00), whereas large increases in RMS and RMF (ES = 1.23-2.49) were found prior to each strength- and endurance-training session. Small differences were found in MVC for the ST group (ES = 0.11) and during CCT-Con for the CCT group (ES = 0.15-0.31).

CONCLUSION

Combining strength training on alternating days with endurance training on consecutive days impairs MVC and running performance at maximal effort and increases RMS and RMF over 6 days.

The repeated bout effect of typical lower body strength training sessions on sub-maximal running performance and hormonal response

PURPOSE

This study examined the effects of two typical strength training sessions performed 1 week apart (i.e. repeated bout effect) on sub-maximal running performance and hormonal.

METHODS

Fourteen resistance-untrained men (age 24.0 ± 3.9 years; height 1.83 ± 0.11 m; body mass 77.4 ± 14.0 kg; VOpeak 48.1 ± 6.1 M kg(-1) min(-1)) undertook two bouts of high-intensity strength training sessions (i.e. six-repetition maximum). Creatine kinase (CK), delayed-onset muscle soreness (DOMS), counter-movement jump (CMJ) as well as concentrations of serum testosterone, cortisol and testosterone/cortisol ratio (T/C) were examined prior to and immediately post, 24 (T24) and 48 (T48) h post each strength training bout. Sub-maximal running performance was also conducted at T24 and T48 of each bout.

RESULTS

When measures were compared between bouts at T48, the degree of elevation in CK (-58.4 ± 55.6 %) and DOMS (-31.43 ± 42.9 %) and acute reduction in CMJ measures (4.1 ± 5.4 %) were attenuated (p < 0.05) following the second bout. Cortisol was increased until T24 (p < 0.05) although there were no differences between bouts and no differences were found for testosterone and T/C ratio (p > 0.05). Sub-maximal running performance was impaired until T24, although changes were not attenuated following the second bout.

CONCLUSIONS

The initial bout appeared to provide protection against a number of muscle damage indicators suggesting a greater need for recovery following the initial session of typical lower body resistance exercises in resistance-untrained men although sub-maximal running should be avoided following the first two sessions.

The effects of strength training and endurance training order on running economy and performance

This study examined the acute effect of strength and endurance training sequence on running economy (RE) at 70% and 90% ventilatory threshold (VT) and on running time to exhaustion (TTE) at 110% VT the following day. Fourteen trained and moderately trained male runners performed strength training prior to running sessions (SR) and running prior to strength training sessions (RS) with each mode of training session separated by 6 h. RE tests were conducted at baseline (Base-RE) and the day following each sequence to examine cost of running (CR), TTE, and lower extremity kinematics. Maximal isometric knee extensor torque was measured prior to and following each training session and the RE tests. Results showed that CR at 70% and 90% VT for SR-RE (0.76 ± 0.10 and 0.77 ± 0.07 mL·kg(-0.75)·m(-1)) was significantly greater than Base-RE (0.72 ± 0.10 and 0.70 ± 0.11 mL·kg(-0.75)·m(-1)) and RS-RE (0.73 ± 0.09 and 0.72 ± 0.09 mL·kg(-0.75)·m(-1)) (P < 0.05). TTE was significantly less for SR-RE (237.8 ± 67.4 s) and RS-RE (275.3 ± 68.0 s) compared with Base-RE (335.4 ± 92.1 s) (P < 0.01). The torque during the SR sequence was significantly reduced for every time point following the strength training session (P < 0.05). However, no significant differences were found in torque following the running session (P > 0.05), although it was significantly reduced following the strength training session (P < 0.05) during the RS sequence. These findings show that running performance is impaired to a greater degree the day following the SR sequence compared with the RS sequence.