Running from Paris to Beijing: biomechanical and physiological consequences

Abstract The purpose of this study was to examine the physiological and biomechanical changes occurring in a subject after running 8,500 km in 161 days (i.e. 52.8 km daily). Three weeks before, 3 weeks after (POST) and 5 months after (POST?5) running from Paris to Beijing, energy cost of running (Cr), knee flexor and extensor isokinetic strength and biomechanical parameters (using a treadmill dynamometer) at different velocities were assessed in an experienced ultra-runner. At POST, there was a tendency toward a 'smoother' running pattern, as shown by (a) a higher stride frequency and duty factor, and a reduced aerial time without a change in contact time, (b) a lower maximal vertical force and loading rate at impact and (c) a decrease in both potential and kinetic energy changes at each step. This was associated with a detrimental effect on Cr (?6.2%) and a loss of strength at all angular velocities for both knee flexors and extensors. At POST?5, the subject returned to his original running patterns at low but not at high speeds and maximal strength remained reduced at low angular velocities (i.e. at high levels of force). It is suggested that the running pattern changes observed in the present study were a strategy adopted by the subject to reduce the deleterious effects of long distance running. However, the running pattern changes could partly be linked to the decrease in maximal strength

Effects of carbohydrates-BCAAs-caffeine ingestion on performance and neuromuscular function during a 2-h treadmill run: a randomized, double-blind, cross-over placebo-controlled study

<p>Abstract</p> <p>Background</p> <p>Carbohydrates (CHOs), branched-chain amino acids (BCAAs) and caffeine are known to improve running performance. However, no information is available on the effects of a combination of these ingredients on performance and neuromuscular function during running.</p> <p>Methods</p> <p>The present study was designed as a randomized double-blind cross-over placebo-controlled trial. Thirteen trained adult males completed two protocols, each including two conditions: placebo (PLA) and Sports Drink (SPD: CHOs 68.6 g.L^-1, BCAAs 4 g.L^-1, caffeine 75 mg.L^-1). Protocol 1 consisted of an all-out 2 h treadmill run. Total distance run and glycemia were measured. In protocol 2, subjects exercised for 2 h at 95% of their lowest average speeds recorded during protocol 1 (whatever the condition). Glycemia, blood lactate concentration and neuromuscular function were determined immediately before and after exercise. Oxygen consumption (<inline-formula><m:math xmlns:m="http://www.w3.org/1998/Math/MathML" name="1550-2783-8-22-i1"><m:mover accent="true"><m:mrow><m:mstyle class="text"><m:mtext class="textsf" mathvariant="sans-serif">V</m:mtext></m:mstyle></m:mrow><m:mo class="MathClass-op">˙</m:mo></m:mover><m:msub><m:mrow><m:mstyle class="text"><m:mtext class="textsf" mathvariant="sans-serif">O</m:mtext></m:mstyle></m:mrow><m:mrow><m:mn>2</m:mn></m:mrow></m:msub></m:math></inline-formula>), heart rate (HR) and rate of perceived exertion (RPE) were recorded during the exercise. Total fluids ingested were 2 L whatever the protocols and conditions.</p> <p>Results</p> <p>Compared to PLA, ingestion of SPD increased running performance (p = 0.01), maintained glycemia and attenuated central fatigue (p = 0.04), an index of peripheral fatigue (p = 0.04) and RPE (p = 0.006). Maximal voluntary contraction, <inline-formula><m:math xmlns:m="http://www.w3.org/1998/Math/MathML" name="1550-2783-8-22-i1"><m:mover accent="true"><m:mrow><m:mstyle class="text"><m:mtext class="textsf" mathvariant="sans-serif">V</m:mtext></m:mstyle></m:mrow><m:mo class="MathClass-op">˙</m:mo></m:mover><m:msub><m:mrow><m:mstyle class="text"><m:mtext class="textsf" mathvariant="sans-serif">O</m:mtext></m:mstyle></m:mrow><m:mrow><m:mn>2</m:mn></m:mrow></m:msub></m:math></inline-formula>, and HR did not differ between the two conditions.</p> <p>Conclusions</p> <p>This study showed that ingestion of a combination of CHOs, BCAAs and caffeine increased performance by about 2% during a 2-h treadmill run. The results of neuromuscular function were contrasted: no clear cut effects of SPD were observed.</p> <p>Trial registration</p> <p>ClinicalTrials.gov, <url>http://www.clinicaltrials.gov</url>, <a href="http://www.clinicaltrials.gov/ct2/show/NCT00799630">NCT00799630</a></p