The effects of a downhill running bout on running economy

No effect of grape juice on exercise-induced muscle damage or performance in male runners: a randomized, placebo-controlled, triple-blind clinical trial

This study aimed to verify the effect of grape juice (Vitis Labrusca) intake on exercise-induced muscle damage (EIMD) and exercise performance parameters (5 km running time-trial (TT), running economy, and countermovement jump (CMJ)). Twenty trained male runners were randomized into two blinded groups and consumed either placebo (n = 9) or grape juice (n = 11) for six consecutive days (600 mL/day). On the fourth day, the participants performed a downhill running (-15%) at speed that elicited 70% V̇O2max for 20 min, to induce muscle damage, followed by assessment of running economy, 5 km TT, and CMJ tests. Blood samples were obtained before and after the exercise tests for quantifying total phenols, creatine kinase (CK), aspartate aminotransferase (AST), and lactate dehydrogenase (LDH). On the sixth day, blood parameters and CMJ were evaluated. A two-way Analysis of covariance (ANCOVA) mixed model was employed for data analysis, the effects were the juice groups, measurement and a interaction between the factors. EIMD was confirmed by increased levels of indirect markers (serum AST and LDH activities) and an impairment in TT and CMJ performances after 48 h. The 5 km TT, economy, and CMJ were compromised after EIMD, to a similar extent in the groups. Blood concentrations of CK, LDH, AST, and total phenolic compounds presented similar time course behavior between the groups, showing no group × time interaction effects. In conclusion, grape juice consumption over 6 days did not attenuate EIMD markers or the impairment in running performance in trained male runners. (ReBEC number: RBR-9jkkvbb).

Foam rolling is an effective recovery tool in trained distance runners

Purpose

Many endurance athletes use foam rolling (FR) to decrease muscle soreness, but it is unclear whether FR effectively treats soreness in this population. Moreover, the effects of FR in highly trained runners are unknown. The aim of this study was to use downhill running (DHR) to induce muscle soreness in runners and to determine the influence of FR on soreness and running performance when compared to sham compression tights.

Methods

Participants performed a running economy (RE) test at 75% of 5-km race speed and a 3-km time trial (TT). In a crossover design, subjects then completed DHR followed by either a FR protocol or wearing sham compression tights. Two days post-DHR, subjects repeated the RE and TT tests. Crossover visits occurred 2-4 weeks later. During RE tests, VO2 and rating of perceived exertion (RPE) were recorded. Passive and active soreness were measured on a scale of 0 (no soreness) to 10 (extreme soreness).

Results

Eight runners (aged 31 ± 7 years; four females; VO2peak 57 ± 7 ml kg-1 min-1) completed the study. Both treatment conditions experienced passive (p = 0.026) and active soreness (p = 0.012) induced by DHR. Active soreness 2 days postDHR was significantly lower after FR than after sham compression tights (p = 0.025). With tights, there was a trend for an increased RPE compared to pre-DHR (p = 0.056).

Conclusions

Foam rolling decreases leg soreness in well-trained runners and attenuates soreness-related increases in perceived exertion during sub-maximal running.

Decreased running economy is not associated with decreased force production capacity following downhill running in untrained, young men

The present study investigated the relationships between changes in running economy (RE) and indirect muscle damage markers following downhill running (DHR) to test the hypothesis that decreased RE after DHR would be associated with decreases in muscle function. Forty-five young men ran downhill (-15%) for 30 min at the velocity corresponding to 70% of their peak oxygen uptake (VO₂peak). Oxygen uptake (VO₂) and other parameters possibly associated with RE (blood lactate concentration, perceived exertion, stride length and frequency) were measured during 5-minute level running at the velocity corresponding to 80%VO₂peak before, immediately after and 1-3 days after DHR. Knee extensor maximal voluntary contraction torque (MVC), rate of torque development, vertical jump performance, muscle soreness and serum creatine kinase activity were assessed at the same time points. The values of the dependent variables were compared among time points by one-way ANOVAs followed by Bonferroni post-hoc tests when appropriate. Pearson's correlation tests were used to examine relationships between changes in VO₂ (RE parameter) and changes in muscle damage parameters. VO₂ during the level run increased (p < 0.05) immediately after DHR (18.3 ± 4.6%) and sustained until 2 days post-DHR (11.7 ± 4.2%). MVC decreased (p < 0.05) immediately (-21.8 ± 6.1%) to 3 days (-13.6 ± 5.9%) post-DHR, and muscle soreness developed 1-3 days post-DHR. The magnitude of changes in VO₂ did not significantly (p < 0.05) correlate with the changes in muscle damage makers (r = -0.02-0.13) nor stride length (r = -0.05) and frequency (r = -0.05). The absence of correlation between the changes in VO₂ and MVC suggests that strength loss was not a key factor affecting RE.

The relationships between age and running performance variables in master runners

Purpose

Peak aerobic capacity (V̇O2peak) declines with age, but running economy (RE) may not. We evaluated VO2peak and RE in master runners and determined whether age is associated with these measures.

Methods

In a cross-sectional study, runners completed two running tests within four weeks of a goal race of 10-26.2 miles. Subjects ran for five min at 88% of predicted maximum heart rate, approximating a marathon-intensity effort (MIE), then performed a V̇O2peak test. Running economy in the MIE was measured using oxygen cost with body mass scaled allometrically (alloV̇O2); energy cost (EC), determined using caloric equivalents; and percent of V̇O2peak (%V̇O2peak). Pearson's correlations were used to determine relationships between age and running performance variables.

Results

Runners (n = 31, 13 females; mean age 54.9 ± 8.4 years) had a mean VO2peak of 52.5 ± 7.9 ml O2 kg-1 min-1. Age was significantly correlated with V̇O2peak (r = - 0.580, p = 0.001) and alloV̇O2 (r = - 0.454, p = 0.034). Age was related to EC in females (r = 0.649, p = 0.042) and MIE V̇O2 in males (r = - 0.600, p = 0.039).

Conclusions

In this population, age was negatively associated with V̇O2peak and alloV̇O2. Females showed a positive relationship between age and EC, while males had a negative correlation between age and MIE V̇O2. Aerobic capacity declines with age, but there may be sex differences in age-related alterations to submaximal running.

Consumption of An Anthocyanin-Rich Antioxidant Juice Accelerates Recovery of Running Economy and Indirect Markers of Exercise-Induced Muscle Damage Following Downhill Running

This study examined the effects of anthocyanin-rich antioxidant juice (AJ) on the recovery of exercise-induced muscle damage (EIMD) and the running economy (RE) following downhill running (DHR). Thirty healthy young men were randomly divided into two blinded groups and consumed either AJ or placebo (PLA) for nine days (240 mL twice-a-day). On day 5, the participants from both groups ran downhill (-15%) for 30 min at 70% of their maximal oxygen uptake (VO₂max) speeds. The changes in RE (oxygen uptake (VO₂) and perceived effort (PE) during 5-min runs at 80%VO₂max) and EIMD (isometric peak torque (IPT), muscle soreness (SOR) and serum creatine kinase activity (CK)) were compared over time and between the groups on the 4 days following DHR. VO₂ and PE increased (p < 0.05) immediately following DHR for both groups and remained elevated for PLA until 48h post-DHR while fully recovering 24 h post-DHR for AJ. SOR was greater (p < 0.05) for PLA throughout the study. CK increased for both groups and was greater (p < 0.05) for PLA at 96 h post-DHR. IPT decreased for both groups but recovered faster for AJ (72 h) compared to PLA (no full recovery). AJ accelerated recovery of RE and EIMD and should be used in specific contexts, but not chronically.

Isometric pre-conditioning blunts exercise-induced muscle damage but does not attenuate changes in running economy following downhill running

Running economy (RE) is impaired following unaccustomed eccentric-biased exercises that induce muscle damage. It is also known that muscle damage is reduced when maximal voluntary isometric contractions (MVIC) are performed at a long muscle length 2-4 days prior to maximal eccentric exercise with the same muscle, a phenomenon that can be described as isometric pre-conditioning (IPC). We tested the hypothesis that IPC could attenuate muscle damage and changes in RE following downhill running. Thirty untrained men were randomly assigned into experimental or control groups and ran downhill on a treadmill (-15%) for 30 min. Participants in the experimental group completed 10 MVIC in a leg press machine two days prior to downhill running, while participants in the control group did not perform IPC. The magnitude of changes in muscle soreness determined 48 h after downhill running was greater for the control group (122 ± 28 mm) than for the experimental group (92 ± 38 mm). Isometric peak torque recovered faster in the experimental group compared with the control group (3 days vs. no full recovery, respectively). No significant effect of IPC was found for countermovement jump height, serum creatine kinase activity or any parameters associated with RE. These results supported the hypothesis that IPC attenuates changes in markers of muscle damage. The hypothesis that IPC attenuates changes in RE was not supported by our data. It appears that the mechanisms involved in changes in markers of muscle damage and parameters associated with RE following downhill running are not completely shared.

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.

Alterations of Neuromuscular Function after the World's Most Challenging Mountain Ultra-Marathon

We investigated the physiological consequences of the most challenging mountain ultra-marathon (MUM) in the world: a 330-km trail run with 24000 m of positive and negative elevation change. Neuromuscular fatigue (NMF) was assessed before (Pre-), during (Mid-) and after (Post-) the MUM in experienced ultra-marathon runners (n = 15; finish time  = 122.43 hours ±17.21 hours) and in Pre- and Post- in a control group with a similar level of sleep deprivation (n = 8). Blood markers of muscle inflammation and damage were analyzed at Pre- and Post-. Mean ± SD maximal voluntary contraction force declined significantly at Mid- (−13±17% and −10±16%, P<0.05 for knee extensor, KE, and plantar flexor muscles, PF, respectively), and further decreased at Post- (−24±13% and −26±19%, P<0.01) with alteration of the central activation ratio (−24±24% and −28±34% between Pre- and Post-, P<0.05) in runners whereas these parameters did not change in the control group. Peripheral NMF markers such as 100 Hz doublet (KE: −18±18% and PF: −20±15%, P<0.01) and peak twitch (KE: −33±12%, P<0.001 and PF: −19±14%, P<0.01) were also altered in runners but not in controls. Post-MUM blood concentrations of creatine kinase (3719±3045 Ul·¹), lactate dehydrogenase (1145±511 UI·L⁻¹), C-Reactive Protein (13.1±7.5 mg·L⁻¹) and myoglobin (449.3±338.2 µg·L⁻¹) were higher (P<0.001) than at Pre- in runners but not in controls. Our findings revealed less neuromuscular fatigue, muscle damage and inflammation than in shorter MUMs. In conclusion, paradoxically, such extreme exercise seems to induce a relative muscle preservation process due likely to a protective anticipatory pacing strategy during the first half of MUM and sleep deprivation in the second half.