european college of sport science

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08:30 - 10:00
Invited symposia
IS-BM07 Cycling
THE BIOENERGETICAL AND BIOMECHANICAL HISTORY OF CYCLING
MINETTI, A.E.
UNIVERSITY OF MILAN
IS-BM07 Cycling
Similarly to the evolutionary struggle towards global mobility observed in animal species on a much wider time scale, human ingenuity
has worked to circumvent the inherent limitation of a given musculo-skeletal system to enhance mobility and speed. In about a century
(1817-1890 CE) the very first individual means of transport moved just by human power, the bicycle and its precursors, has been invented
and rapidly developed up to a standard design that was only refined successively. From the ‘Hobby Horse’ to modern bikes, a short time
scale evolution in manufacturing technology has solved a progression of physiological and biomechanical problems related to how to
make the best use of the same muscles in spite of an increasing progression speed. By arranging a set of experiment where the same
group of subjects rode replicas of the most significant bicycle models appeared as breakthrough in the 19th century, it was possible to
dissect the relevant components of the mechanical work as determinants of the metabolic energy required to travel at the same speeds.
This resulted in a study (Minetti et al 2001) about the evolutionary improvement in bicycling economy and its biomechanical explanation.
The total mechanical work has been calculated as the sum of the ’external’ component, due to the need to overcome rolling resistance
and air drag, and the ‘internal work’, related to the movement of the lower limbs with respect to the body centre of mass (BCOM) during
pedalling. The general conclusion from that study was that each newly invented bicycle model, while changing the partitioning of the
three work components associated to a higher travelling speed, allowed muscles to operate at the same, maximal contraction efficiency.
A later investigation (Minetti 2001) on the metabolic equivalent of the internal work in cycling seemed to confirm the validity of the model
equation designed for the historical study. A more accurate biomechanical analysis suggested that, despite the minimal change in
BCOM due to pedalling, most of the internal work is devoted to maintain constant the angular speed of the chain wheel. Another important
and often neglected component of the internal work, namely the joint/tissue friction, could contribute to better explain the overall
economy of cycling.
REFERENCES
Minetti A. E., J. Pinkerton and P. Zamparo. From bipedalism to bicyclism: evolution in bioenergetics and biomechanics of historic bicycles.
Proc. R. Soc. B 268: 1351-1360, 2001.
Minetti A. E.. The metabolic equivalent of internal work in cycling. 4th World Congress of Biomechanics, Calgary, 2002.
FACTORS AFFECTING CYCLING CADENCE CHOICE AND CADENCE INFLUENCE ON PERFORMANCE
HANSEN, E.A.
NORWEGIAN SCHOOL OF SPORT SCIENCES
A considerable interest among researchers, coaches, and cyclists for cadence choice during submaximal cycling dates nearly 100 years
back (Benedict & Cathcart, 1913). The current knowledge of factors affecting the freely chosen cadence and of the influence of cadence
choice on performance has been summarized recently (Hansen & Smith, 2009). In particular, within the past 10 years, a number of papers
brought novel insight into the topic. For example, under the influence of central pattern generators, which are constituted of neural
networks in the spinal cord, a robust innate voluntary motor rhythm has been suggested as the primary basis for rhythmic movements
(Zehr, 2005) including freely chosen cadence (Hansen & Ohnstad, 2008). This might clarify the cadence paradox, which has been described
as the freely chosen cadence during low to moderate submaximal cycling being considerably higher and thereby less economical
than the energetically optimal cadence (Kohler & Boutellier, 2005). Despite that central pattern generators apparently are important
for the robust and highly individual base of the freely chosen cadence during submaximal cycling, the possible influence of factors internal
and external to the cyclist on the choice of cadence under certain circumstances should be acknowledged. Thus, a number of factors
including for example age (Balmer et al., 2008), power output (Hansen et al., 2002), and road gradient (Lucia et al., 2001), have been
reported to affect the choice of cadence to some extent. But, it is likely that, during unrestricted pedalling, sensory feedback of changes to
external conditions as well as internal conditions merely fine-tunes the innate motor rhythm. Finally, as to cadence influence on performance;
during high intensity cycling, close to the maximal aerobic power output, cyclists choose an energetically economical cadence
(Brisswalter et al., 2000) that is also favourable for performance (Nesi et al., 2004). However, the choice of a relatively high cadence
during cycling at low to moderate intensity is energetically uneconomical and could compromise performance during prolonged cycling
(Hansen et al., 2006).
References
Balmer J et al. (2008) J Sports Sci 26: 57-62
Benedict FG & Cathcart EP (1913) Carnegie Institution of Washington, Washington, D. C.
Brisswalter J et al. (2000) Int J Sports Med 21: 60-64
Hansen EA et al. (2002) Acta Physiol Scand 176: 185-194
Hansen EA et al. (2006) Eur J Appl Physiol 98: 227-233
Hansen EA & Ohnstad AE (2008) Exp Brain Res 186: 365-373
Hansen EA & Smith G (2009) Int J Sports Physiol Perform 4: 3-17
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ANNUAL CONGRESS OF THE EUROPEAN COLLEGE OF SPORT SCIENCE