International Journal of Sports Medicine: Progress and Innovation in Cycling Science 2001 - 2007

As stated on the Journal Website, the main aim of the International Journal of Sports Medicine (IJSM) is to “provide a forum for the publication of papers dealing with both basic and applied information that advance the field of sports medicine and exercise science, and offer a better understanding of biomedicine”. Cycling is, of course, a popular mode of exercise chosen by both applied and basic investigators who publish in IJSM. There are many medical-related issues that are relevant to competitive cyclists, who are also a popular choice for research participants in general studies of exercise science. This ubiquity of cycling and cyclists across different types of studies has encouraged me, with this editorial, to highlight the studies on cycling that have recently (2001 - 2007) been published in IJSM. It is clear that these studies have helped Sport and Exercise Scientists to gain a “better understanding of biomedicine”.

Probably the most important development in cycling science over the last 10 years has been the introduction and refinement of bicycle-mounted power measurement devices. Such devices conventionally involve the measurement of force using strain gauges sited in the transmission system (i.e., the pedals, the cranks, the chain or the rear-wheel hub) of the bicycle. Authors of IJSM manuscripts have kept pace with these developments via careful examinations of the validity and reliability of power measurements. For example, Millet et al. [[17]] found that the Polar S710 mobile device, although less expensive, disagreed systematically with the SRM “power-cranks”, especially at high power outputs. Similar systematic error was found between the Axiom Powertrain stationary ergometer and some SRM power-cranks which were fitted to this ergometer [[1]]. However, power measurements for the Powertap and SRM devices were found by Bertucci et al. [[2]] to agree sufficiently well for interchangeable use. In agreement with these authors, Paton and Hopkins [[22]] employed a novel data analysis technique to report that errors were similar for the Powertap and SRM devices, but slightly larger for the Kingcycle stationary ergometer. Unlike the Powertap and SRM devices, which employ strain gauges to measure power directly within each pedal stroke, ergometers such as the Kingcycle measure power output indirectly from resulting wheel-speed, not unlike older ergometers that were based on the speed of a fly-wheel attached to the cranks of the ergometer. Cycling scientists are, therefore, in the unusual situation of the ambulatory on-bike power measuring devices probably being more accurate than the fly-wheel or bike-wheel speed-based stationary ergometers that have, in the past, been popular choices for laboratory measurements. New devices will continue to emerge and be validated by IJSM authors, e.g. [[26]]. One hopes that the price of these new devices will fall as they become more common.

Of course, the technical source of error associated with an ergometer is just one component of variability inherent in any test protocol administered to real athletes. Authors of IJSM publications have also worked hard to examine the appropriateness of several cycling protocols, irrespective of which ergometer they are performed with. In terms of incremental cycling tests, Weston et al. [[29]] found that assessment of ventilatory thresholds was unaffected by the rate of power increase during a “ramped” cycling protocol. However, Van Schuylenbergh et al. [[27]] found that it was not possible to predict the power or heart rate that corresponds to maximal lactate steady state using a single graded cycling test. In addition, Brickley et al. [[3]] found that variables measured during a 90-s all-out cycling test could not be used to predict V·O_2max or critical power.

There have also been some recent efforts to increase the external validity of cycling tests. Doherty et al. [[5]] validated a cycling protocol which combined a period of steady-state cycling (allowing measurement of physiological responses) with a performance component. Laursen et al. [[11]] found that the coefficient of variation for reproducibility of 40-km time trial performance is below 1 %, providing cyclists are adequately familiarised. Smith et al. [[24]] also found high reproducibility for 40-km time trials, whether these were performed in the laboratory or “in the field”. The repeated high-intensity efforts that comprise many cycling disciplines have been simulated in several studies [[4], [6]] and “real-world” problems, such as optimal starting strategy for time trials, have been investigated [[15]]. Such externally valid protocols are welcome developments, telling us much more than any simple steady-state time to exhaustion test, which have been commonly employed in the past.

Many authors of IJSM manuscripts have managed to recruit world-class cyclists for their detailed studies on ultra-endurance events. Such invasive research on top-level athletes in unparalleled in any other sport. Most notably, Alexandro Lucia and colleagues have continued to examine the physiological responses (e.g., most recently, the immune responses) of professional riders in the Vuelta a España stage race [[16]]. Neumayr et al. [[19]] even found disturbances to immune function after a one-day 230-km cycling event. However, Hue et al. [[9]] found that resting thermoregulatory and some haematological variables were unaffected during a 9-day cycling stage race, and Vogt et al. [[28]] found that professional cyclists are not in negative energy balance during intensive pre-season training. In less-trained subjects, Ruiz et al. [[23]] found that a 95-km mountain bike competition held at moderate altitude increased the susceptibility of plasma lipids to peroxidation by about 72 %. Such differences between world-class and recreational cyclists might of course be explained by genetic factors. Interestingly, Lucia et al. [[14]] showed that professional road cyclists competing in major stage races may be genetically different even from other endurance athletes such as elite runners. This suggestion of a specific cycling “genotype” agrees with other observations that there are unique rheological [[7]] and metabolic [[10]] responses to cycling compared to running exercise of the same relative intensity, although cycling efficiency seems to be stable across cycling ability levels [[18]].

Finally, there are noteworthy studies published in IJSM covering clinical and health-related issues in cycling, including those relevant to doping and its control. It seems that the effects of ultra-endurance cycling on renal [[20]] and prostatic [[12]] function are minimal. Sperm count and motility are also normal in endurance cyclists, although there could be cycling-related alterations in sperm morphology [[8]]. Sommer et al. [[25]] reported a cycling-mediated transient deficiency in penile perfusion due to perineal arterial compression, although the long-term clinical effects of such “penile numbness” are not known. Neumayr et al. [[21]] examined the effects of exercise on haematocrit measurements and concluded that their use in doping control, either before or after exhausting cycling exercise, is robust.

As an editor of IJSM, I continue to welcome letters about published manuscripts or general commentaries from cycling scientists. In one of these recent communications, Lippi [[13]] detailed the new anti-doping programme forwarded by the International Cycling Union and maintained that the proposed procedures were the most rigorous in world sport. Let us hope that the subsequent cases of doping, or suspected doping, amongst riders in the 2007 Tour de France will finally give “clean” competitive cyclists adequate confidence in these new doping controls, and that other sporting governing bodies consider adopting them.

Greg Atkinson

References

• 1 Bertucci W, Duc S, Villerius V. et al . Validity and reliability of the axiom powertrain cycle ergometer when compared with an SRM powermeter.  Int J Sports Med. 2005;  26 59-65
• 2 Bertucci W, Duc S. et al . Validity and reliability of the PowerTap mobile cycling powermeter when compared with the SRM device.  Int J Sports Med. 2005;  26 868-873
• 3 Brickley G, Dekerle J. et al . Assessment of maximal aerobic power and critical power in a single 90-s isokinetic all-out cycling test.  Int J Sports Med. 2007;  28 414-419
• 4 Coleman D A, Wiles J D. et al . Reliability of sprint test indices in well-trained cyclists.  Int J Sports Med. 2005;  26 383-387
• 5 Doherty M, Balmer J. et al . Reliability of a combined 3-min constant load and performance cycling test.  Int J Sports Med. 2003;  24 366-371
• 6 Falgairette G, Billaut F, Giacomoni M. et al . Effect of inertia on performance and fatigue pattern during repeated cycle sprints in males and females.  Int J Sports Med. 2004;  25 235-240
• 7 Galy O, Hue O. et al . Blood rheological responses to running and cycling: a potential effect on the arterial hypoxemia of highly trained athletes?.  Int J Sports Med. 2005;  26 9-15
• 8 Gebreegziabher Y, Marcos E. et al . Sperm characteristics of endurance trained cyclists.  Int J Sports Med. 2004;  25 247-251
• 9 Hue O, Voltaire B, Hertogh C. et al . Heart rate, thermoregulatory and humoral responses during a 9-day cycle race in a hot and humid climate.  Int J Sports Med. 2006;  27 690-696
• 10 Knechtle B, Muller G. et al . Fat oxidation in men and women endurance athletes in running and cycling.  Int J Sports Med. 2004;  25 38-44
• 11 Laursen P B, Shing C M. et al . Reproducibility of a laboratory-based 40-km cycle time-trial on a stationary wind-trainer in highly trained cyclists.  Int J Sports Med. 2003;  24 481-485
• 12 Lippi G, Corgnati A, Salvagno G. et al . Total and free PSA serum concentrations are not influenced by extensive physical exercise and bicycle riding.  Int J Sports Med. 2005;  26 79-81
• 13 Lippi G. The international cycling union unveils new anti-doping program. How much is enough?.  Int J Sports Med. 2007;  28 446-447
• 14 Lucia A, Gomez-Gallego F. et al . Is there an association between ACE and CKMM polymorphisms and cycling performance status during 3-week races?.  Int J Sports Med. 2005;  26 442-447
• 15 Mattern C O, Kenefick R W. et al . Impact of starting strategy on cycling performance.  Int J Sports Med. 2001;  22 350-355
• 16 McKune A J, Smith L L. et al . Changes in mucosal and humoral atopic-related markers and immunoglobulins in elite cyclists participating in the Vuelta a Espana.  Int J Sports Med. 2006;  27 560-566
• 17 Millet G P, Tronche C. et al . Validity and reliability of the Polar® S710 mobile cycling powermeter.  Int J Sports Med. 2003;  24 156-161
• 18 Moseley L, Achten J. et al . No differences in cycling efficiency between world-class and recreational cyclists.  Int J Sports Med. 2004;  25 374-379
• 19 Neumayr G, Ludwiczek O. et al . The impact of prolonged strenuous endurance exercise on interleukin 18 and interleukin 18 binding protein in recreational cyclists.  Int J Sports Med. 2005;  26 836-840
• 20 Neumayr G, Pfister R. et al . Renal function and plasma volume following ultramarathon cycling.  Int J Sports Med. 2005;  26 2-8
• 21 Neumayr G, Pfister R. et al . Short-term effects of prolonged strenuous endurance exercise on the level of haematocrit in amateur cyclists.  Int J Sports Med. 2002;  23 158-161
• 22 Paton C D, Hopkins W G. Ergometer error and biological variation in power output in a performance test with three cycle ergometers.  Int J Sports Med. 2006;  27 444-447
• 23 Ruiz J R, Ortega F B, Castillo M J. et al . Increased susceptibility to plasma lipid peroxidation in untrained subjects after an extreme mountain bike challenge at moderate altitude.  Int J Sports Med. 2006;  27 587-589
• 24 Smith M F, Davison R CR. et al . Reliability of mean power recorded during indoor and outdoor self-paced 40 km cycling time-trials.  Int J Sports Med. 2001;  22 270-274
• 25 Sommer F, Konig D. et al . Impotence and genital numbness in cyclists.  Int J Sports Med. 2001;  22 410-413
• 26 Stapelfeldt B, Mornieux G. et al . Development and evaluation of a new bicycle instrument for measurements of pedal forces and power output in cycling.  Int J Sports Med. 2007;  28 326-332
• 27 Van Schuylenbergh R, Eynde B V. et al . Correlations between lactate and ventilatory thresholds and the maximal lactate steady state in elite cyclists.  Int J Sports Med. 2004;  25 403-408
• 28 Vogt S, Heinrich L. et al . Energy intake and energy expenditure of elite cyclists during preseason training.  Int J Sports Med. 2005;  26 701-706
• 29 Weston S B, Gray A B. et al . Effect of ramp slope on ventilation thresholds and V·O₂peak in male cyclists.  Int J Sports Med. 2002;  23 22-27