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Fonda, B. and Šarabon, N.: BIOMECHANICS AND ENERGETICS OF UPHILL ... Kinesiology 44(2012) 1:5-17
5
BIOMECHANICS AND ENERGETICS
OF UPHILL CYCLING: A REVIEW
Borut Fonda1 and Nejc Šarabon1,2
1S2P Ltd., Laboratory for Motor Control and Motor Behaviour, Ljubljana, Slovenia
2University of Primorska, Science and Research Centre, Institute for Kinesiology Research,
Koper, Slovenia
Review
UDC: 577.35:612.766:796.61:796.015
Abstract:
The winners of the major cycling 3-week stage races (i.e. Giro d’Italia, Tour de France, Vuelta a Espana)
are usually riders who dominate in the uphill sections of the race. Amateur cyclists, however, will often
avoid uphill terrain because of the discomfort involved. Therefore, understanding movement behavior during
uphill cycling is needed in order to find an optimum solution that can be applied in practice. The aim of this
review is to assess the quality of research performed on biomechanics and the energetics of uphill cycling.
Altogether we have analyzed over 40 articles from scientific and expert periodicals that provided results on
energetics, pedal and joint forces, economy and efficiency, muscular activity, as well as performance and
comfort optimization during uphill cycling. During uphill cycling, cyclists need to overcome gravity and
in order to achieve this, some changes in posture are necessary. The main results from this review are that
changes in muscular activity are present, while on the other hand pedal forces, joint dynamics, and cycling
efficiency are not substantially altered during seated uphill cycling compared to cycling on level terrain.
In contrast, during standing uphill cycling, all of the previously mentioned measures are different when
comparing either seated uphill cycling or level terrain cycling. Further research should focus on outdoor
studies and steeper slopes.
Key words: performance, efficiency, biomechanics, physiology, optimization
Introduction
Cycling has been the subject of discussion in
many of the published scientic reviews (Ericson,
1986; Wozniak Timmer, 1991; di Prampero, 2000;
Jeukendrup & Martin, 2001; Atkinson, Davison,
Jeukendrup, & Passeld, 2003; Faria, Parker, &
Faria, 2005; Bini & Diefenthaeler, 2009; Hug &
Dorel, 2009). Research in cycling has generally
concentrated either on a set of particular and prac-
tically relevant problems such as enhancing per-
formance (Jeukendrup & Martin, 2001; Faria, et al.,
2005), improving rehabilitation protocols (Ericson,
1986), improving comfort (Gámez, et al., 2008), and
preventing the harmful effects caused by cycling
(Burke, 1994; de Vey Mestdagh, 1998; Silberman,
Webner, Collina, & Shiple, 2005), or on the more
basic aspects of locomotion during cycling (Too,
1990; Coyle, et al., 1991; di Prampero, 2000; Bini
& Diefenthaeler, 2009; Fonda & Sarabon, 2010a).
All of the previously mentioned reviews were
mainly focused on studies that included level terrain
cycling with little or no emphasis on uphill cycling.
From a racing point of view, uphill cycling can often
be the deciding factor that determines the winner
(Bertucci, Grappe, Girard, Betik, & Rouillon 2005;
Hansen & Waldeland, 2008). This can be deduced
from the fact that in previous years, the winners
of the major 3-week stage races (i.e. Giro d’Italia,
Tour de France, Vuelta a Espana) have generally
been riders who excelled in the hilly climbing
sections of the races. On the other hand, in leisure
cycling, if cyclists are sufciently trained to cope
with hills, uphill terrains often cause discomfort
due to different mechanical loads on the spine.
Consequently, many leisure cyclists tend to avoid
hills (Fonda, Panjan, Markovic, & Sarabon, 2011).
During uphill cycling, riders need to overcome
gravity, which increases the demands for mechani-
cal power. Because of the inclination of the surface,
they need to adapt their posture for two primary
reasons: rst, to avoid lifting the front wheel and,
second, to ensure that they keep a stable position on
the saddle, so that they do not slide off (Figure 1).
Mountain bikers have to succeed in overcoming
Kinesiology 44(2012) 1:5-17Fonda, B. and Šarabon, N.: BIOMECHANICS AND ENERGETICS OF UPHILL ...
6
even more demanding terrain conditions: they need
to ensure that there is enough traction on the rear
wheel while simultaneously making sure the front
wheel stays on the ground. To accomplish this, the
mountain bikers have to shift their body forward on
the saddle and ex their trunk (by leaning forward).
This change in posture alters some of the charac-
teristics of pedaling. Such changes can be reected
in (1) different mechanical demands (di Prampero,
2000), (2) changed economy and efciency (Mo-
seley & Jeukendrup, 2001), (3) altered cycling kin-
ematics and kinetics (Bertucci, et al., 2005), and
(4) modied neuromuscular activation patterns
(Sarabon, Fonda, & Markovic, 2011). Changes
can also be reected in health-related issues dur-
ing cycling. For example, lower back pain is one
of the most common cycling injuries (Marsden &
Schwellnus, 2010) and based on previous research
(Salai, Brosh, Blankstein, Oran, & Chechik, 1999)
we can assume that the lower back pain issue can
intensify when cyclists adjust their posture due to
uphill terrain characteristics (e.g. increased tensile
forces on lumbar vertebra).
the presented experimental data and with some
directions for future research in the eld.
When searching through the available litera-
ture, we focused on professional and scientic pa-
pers from the following databases: Pubmed, Sci-
enceDirect, and Springerlink. We combed through
them by using keywords such as biomechanics, en-
ergetics, equation, forces, joints, EMG (i.e. electro-
myography) and performance, while including the
words uphill and cycling. We noted over 40 profes-
sional and scientic papers. In the review tables
(Table 1, Table 2 and Table 3) we have included 13
articles that directly reported studies on biomechan-
ics and/or energetics of uphill cycling.
Equations of uphill cycling
During level terrain cycling at constant speed,
the amount of energy wasted against gravitational
forces with each pedal stroke is minimal, although
inertial forces have been reported to have some in-
uence on pedal forces (Kautz & Hull, 1993). There-
fore, a cyclist performs almost all of the mechanical
work (W
C
) against two main opposing forces (Equa-
tion 1): the rolling resistance (RR) and
the air resistance (R
A
), whose resultant
is the total resistance (RT) (van Ingen
Schenau & Cavanagh, 1990). RR is the
energy loss as the wheels roll along the
surface and it depends substantially on
the mass of the bicycle and rider sys-
tem, the acceleration of gravity, and
a coefcient describing the ination
pressure of the tires, the characteris-
tics of the surface and the type of the
tires (di Prampero, Cortili, Mognoni,
& Saibene, 1979). The RA is a func-
tion of the frontal plane area of the cy-
clist and the bike, the air density and
the air velocity. At higher speeds, R
R
becomes a progressively smaller frac-
tion of RT. In practice, the estimation
of the frontal plane area can be done
either by using elaborate tests, such as
a rolldown (de Groot, Sargeant, & Geysel, 1995),
tractive towing (di Prampero, et al., 1979) or wind-
tunnel experiments (Kyle, 1991), or by more simpli-
ed methods, such us using photographic weighing
or planimetry (Olds & Olive, 1999). It is also com-
mon to measure the RA rst (using, for example, a
wind tunnel) and then calculating the frontal plane
area from that estimate.
WC = a + b · v2 Equation 1
CC = WC · η-2 Equation 2
In Equation 1, WC is the mechanical work per-
formed per unit of distance, v is the air speed and,
a and b are constants for RR and RA per unit of dis-
tance, respectively. The energy cost (C
C
) of cycling
depends on overall cycling efciency (η) (Equation
Figure 1. Differences in posture between level terrain (A) and uphill cycling
(B). The hip angle (α), shoulder angle (β), and elbow angle (γ) are all smaller
during uphill cycling. The position on the saddle is shifted forward (a) and
the back is more rounded (b) during uphill cycling.
Understanding movement patterns during up-
hill cycling is necessary when searching for opti-
mal solutions or enhancements, which can be then
applied in practice. In the rst part of this paper we
will focus on the equations of motion of cyclists
during uphill cycling and try to address some of
the practical implications in this eld. The next
chapter focuses on economy and efciency during
uphill cycling. Patterns of kinetics and kinematics
during uphill cycling are subsequently presented,
with an emphasis on pedal forces, joint moments
and joint movements. Neuromuscular alterations
during uphill cycling are presented in the next part.
In the nal part, some of the practical solutions for
improving uphill cycling are addressed. The paper
concludes by summarizing the applied values of
Fonda, B. and Šarabon, N.: BIOMECHANICS AND ENERGETICS OF UPHILL ... Kinesiology 44(2012) 1:5-17
7
2). The mechanical efciency of cycling is not far
from 25%; however, it depends upon the cadence
(pedal frequency) which increases from 42 to 60
rpm as the power output is increased from 50 to 300
W (di Prampero, 1986, 2000; Ericson, 1988). How-
ever, well-trained cyclists usually opt for higher pe-
daling frequencies (Kohler & Boutellier, 2005). In
general, during uphill cycling, cyclists develop high
forces at low cadences that are likely to be more
economical; in contrast, on at ground, they in-
crease their cadence because their aerodynamic
posture does not allow for high force production
(Mognoni & di Prampero, 2003). In contrast, Dorel,
Couturier, and Hug (2009) showed that cyclists can
apply greater forces at the power phase of the crank
cycle with an aerodynamic posture compared to an
upright posture. The reason why competing cyclists
opt for higher pedal frequencies instead of the op-
timal rate was discussed by di Prampero in his re-
view (di Prampero, 2000) with plausible explana-
tions in the reduced anaerobic energy releases to
compensate for the slight fall in efciency. Higher
cadences were then explained by overall muscle
activation (MacIntosh, Neptune, & Horton, 2000),
reduced joint moments (Marsh, Martin, & Sander-
son, 2000) and consequently lower resistive force
to sustain similar power output.
The mechanical power (P
C
) required to cycle
at a constant speed is given by the product of W
C
and the speed (s) (Equation 3), while the metabolic
power (EC) is dened as the product of CC and s
(Equation 4). Both, PC and EC, are expressed in
Watts, since according to SI units, CC is expressed
in J/m and s in m/s.
PC = WC · s Equation 3
EC = CC · s Equation 4
Equations 1, 2, 3 and 4 become practical when
all data is known. By using the commercially avail-
able power meters (e.g. SRM® or Cycleops Power
Tab®) the power output and velocity are known,
therefore the R
T
can be calculated as external power
output divided by the velocity (Grappe, et al., 1999;
Lim, et al., 2011). With a constant tire pressure and
a change in body position, only RA is altered. This
technique could be extremely valuable in helping
cyclists, coaches and scientists to predict and im-
prove cycling performance (Lim, et al., 2011).
During uphill cycling, at a given power output,
the RA becomes a relatively smaller fraction of the
RT and the main opposing force becomes accelera-
tion due to gravity. Opposing forces during uphill
cycling are summarized in Figure 2.
The mechanical work performed against grav-
ity (WCG) when cycling uphill is given by the prod-
uct of the overall moving mass (M), the accelera-
tion due to gravity (g) and vertical displacement
(h). When expressed per unit of distance covered
along the road (d) (Equation 5), mechanical work
can be expressed as the product of M, g and sinus γ
(Equation 6), where γ is the angle of the road slope.
WCG = M · g · h · d-1 Equation 5
WCG = M · g · sin γ Equation 6
A more detailed description of the W
C
can be
achieved by including the RR and RA in the calcula-
tions (Equation 7).
WC = a + b · s2 + M · g · sin γ Equation 7
The CC can be calculated by substituting a and b
in Equation 7 with the constants for metabolic ener-
gy dissipated against RR (α, since α = a · η-1) and RA
(β, since β = b · η-1), respectively, and dividing the
last term by η (Equation 8). The EC can be further
estimated by the same principle used during level
terrain cycling as a product of CC and s (Equation
9). The mechanical efciency has been shown not
to change during uphill cycling (Millet, Tronche,
Fuster, & Candau, 2002).
CC = α + β · s2 + M · g · sin γ · η-1 Equation 8
EC = α · s + β · s3 + M · g · s · sinγ · η-1 Equation 9
With these equations, we can estimate some of
the important practical values. For example, in his
review, di Prampero (2000) estimated the maxi-
mal incline of the slope that the cyclist could over-
come. This is possible if the subjects’ maximal EC
is known and the lowest speed value at which the
cyclist does not lose his/her balance is assigned.
However, these estimations can only be made for a
smooth terrain and with the use of an appropriate
gear system to ensure optimum pedal frequency at
a very low speed.
Furthermore, by using the results from Equa-
tion 8 in Equation 4, and knowing EC, the velocity
can be calculated on every specic slope (Welber-
gen & Clijsen, 1990). Welbergen and Clijsen (1990)
estimated the incline at which the cyclist would ben-
et from an upright position when compared to the
Figure 2. Main opposing forces during uphill cycling. Where
g is acceleration due to gravity; RA is aerodynamic drag,
RR are tractive resistive forces, and γ is angle of the terrain.
Kinesiology 44(2012) 1:5-17Fonda, B. and Šarabon, N.: BIOMECHANICS AND ENERGETICS OF UPHILL ...
8
standard racing position. The E
C
for the upright po-
sition is 20% higher than for the racing position
(Welbergen & Clijsen, 1990). With this informa-
tion, the authors estimated that the incline where
air resistance was no longer the limiting factor was
approximately 7.5%. This information could benet
both coaches and cyclists regarding the posture they
should adopt during the uphill sections of a race.
Efficiency and economy during uphill
cycling
Cycling efficiency
Cycling efciency has been described as the
ratio of work accomplished to energy cost, which
depends on the cadence (Gaesser & Brooks, 1975),
feet position (Disley & Li, 2012), body position
(Ryschon & Stray-Gundersen, 1991), and muscle
ber type (Coyle, Sidossis, Horowitz, & Beltz,
1992). Several calculations for efciency have
been proposed, mainly differentiated by a baseline
correction factor that is used to correct the estimate
of the energy expenditure and therefore of the
measured level of efciency (Gaesser & Brooks,
1975; Millet, et al., 2002). Gross cycling efciency
has been demonstrated to be highly correlated with
cycling performance and has a low variability and
detects smaller changes in exercise efciency over
several trials (Millet, et al., 2002).
Millet et al. (2002) examined the cycling gross
efciency during level 5.3% uphill seated and
5.3% uphill standing conditions. The gradient does
not appear to be a factor that inuences cycling
efciency at the same power output. Similarly,
Leirdal and Ettema (2011) found no signicant
differences in gross efciency, force effectiveness
and dead center size between the level and 11%
uphill cycling conditions. However, it is likely
that the efciency would be altered during steeper
slopes, mainly because of the decrease in cadence
(Swain & Wilcox, 1992).
Cycling economy
The term is used as a measure of oxygen con-
sumption per unit of power output (Moseley &
Jeukendrup, 2001). It can also be expressed as the
oxygen consumption required to cycle at a given
speed (Swain & Wilcox, 1992). The factors that
inuence cycling economy vary with the conditions
under which cycling is performed (Table 1). Swain
and Wilcox (1992) showed that a well-trained
cyclist is more economical when using a higher
pedaling frequency during seated uphill cycling
than using a lower pedal frequency in either the
seated or standing position. In contrast, Harnish,
King and Swensen (2007) showed that trained
cyclists are equally economical using high or low
cadences, although they found a signicant increase
in ventilation (6%) and breathing frequency (8%)
during standing uphill cycling when compared to
the seated position. That could be explained by the
rhythmic pattern of breathing in coordination with
the locomotion during pedaling while standing.
The results obtained by Millet et al. (2002)
showed that there are no signicant differences in
economy during uphill cycling (seated and stand-
ing) compared to level terrain. However, heart rates
were found to be higher (6%) during standing uphill
cycling as opposed to the seated position.
Increased ventilation during standing uphill
cycling was accompanied by an increase in
breathing frequency, which seems to be related to
the rhythmic pattern of pedaling. Uphill cycling
does not appear to be a factor that inuences cycling
efciency, although more research is necessary,
especially during steeper slopes, to conrm these
conclusions.
Table 1. A review of studies on efficiency and economy during uphill cycling
Publication Cyclists Slope Findings
Millet et al. (2002) 8 well-trained
cyclists 5.3%
Gross cycling efficiency and economy were not significantly different
among the level seated, uphill seated, or uphill standing position.
Harnish et al. (2007) 8 well-trained
cyclists 5%
Ventilation and breathing frequency were significantly higher during
standing compared to seated uphill cycling. Trained cyclists are in general
equally economical using high or low cadences during uphill cycling.
Swain and Wilcox
(1992)
14 well-trained
cyclists 10%
Cyclists were more economical using a high cadence (84 rpm) in seated
position than by using a low cadence (41 rpm) in either the seated or
standing position.
Hansen and
Waldeland (2008)
10 well-trained
cyclists 10%
Trained cyclists performed better standing rather than seated at the
highest intensities. The intensity of exercise that characterized the
transition from seated to standing was found to be approximately 94% of
maximal aerobic power. At lower power outputs, there was no difference
between seated or standing uphill cycling.
Leirdal and Ettema
(2011)
10-well trained
cyclists 11%
There was no difference in gross efficiency, force effectiveness and dead
centre size between a level and inclined cycling condition.
Fonda, B. and Šarabon, N.: BIOMECHANICS AND ENERGETICS OF UPHILL ... Kinesiology 44(2012) 1:5-17
9
Kinematics and the kinetics of uphill
cycling
Pedal and crank kinetics during uphill
cycling
Alterations in kinetic patterns of pedal force
and crank torque due to various changes during
cycling have only been investigated in a few stud-
ies. A major problem is the equipment needed to
evaluate the forces and torque on the pedal or crank.
Instrumented pedals (Álvarez & Vinyolas, 1996;
Hoes, Binkhorst, Smeekes-Kuyl, & Vissers, 1968;
Reiser, Peterson, & Broker, 2003) which normally
measure the forces applied at the foot/pedal interface
were used to: study the kinetics under different
cadence and workload conditions (Kautz, Feltner,
Coyle, & Baylor, 1991), as an input for inverse dyna-
mics to evaluate joint moments (Redeld & Hull,
1986), or to assess the determinants of performance
in cycling (Coyle, et al., 1991). Caldwell, McColle,
Hagberg and Li (1998) studied the crank torque
prole while moving uphill (8%) and level terrain
cycling and found no signicant differences in the
general crank torque prole when comparing at
the same cadence in a seated condition. According
to Bertucci et al. (2005), the reasons for this can
be found in the crank inertial load, which is lower
during uphill cycling because it depends on the
gear ratio and the mass of the cyclist (Hansen,
Jørgensen, Jensen, Fregly, & Sjøgaard, 2002).
Hansen et al. (2002) observed that the crank torque
prole was modied by varying the crank inertial
load. They showed that when cycling with a high
crank inertial load, peak torque was signicantly
higher. Crank-to-torque proles observed during
laboratory conditions are probably affected by the
crank inertial load and the data should thus be
interpreted with caution. The latter was conrmed
by Bertucci, Grappe and Groslambert (2007) who
found alterations in the crank torque prole during
laboratory conditions compared to outdoor road
conditions. However, their data should be taken
with caution, as they used the SRM torque analysis
system, which has been shown to underestimate
peak torque from bilateral measures (Bini, Hume,
& Cerviri, 2011). Minor effects on the crank torque
prole could also be present due to the mechanical
properties (i.e. stiffness and damping) of the bicycle
ergometer.
The pedal and crank kinetics during uphill
cycling studies are presented in Table 2.
In outdoors conditions, and at the same ca-
dences (80 rpm), Bertucci et al. (2005) reported
that the crank torque prole was slightly modied
during uphill cycling compared to a level terrain.
The highest difference was observed at 45° of the
crank cycle (30.7 vs. 22.8 Nm for level and uphill
terrain, respectively), although no differences were
observed for peak values. These results vary from
those of Hansen et al. (2002) who found differenc-
es in peak torque during cycling with a high and
low crank inertial load. The differences could be
explained by the fact that the study of Hansen et
al. (2002) was conducted on a motorized treadmill
with good control over the velocity, while in the
eld study of Bertucci et al. (2005) the cycling ve-
locity was more prone to oscillations. According to
the data gathered by Bertucci et al. (2007) the peak
torque and minimal torque both occur 5° later in the
crank cycle, even though the values of the torque
were very similar.
Joint moments and kinematics during
uphill cycling
The studies on joint kinematics and kinetics
during cycling were mainly performed on level ter-
rain (Leirdal & Ettema, 2011; Bini & Diefenthaeler,
2010; Bini, Tamborindeguy, & Mota, 2010; Bini,
Diefenthaeler, & Mota, 2010; Ericson, Bratt, Nisell,
Németh, & Ekholm, 1986). Despite being practical-
ly important, these biomechanical studies of uphill
cycling are relatively unknown. The authors of this
review were only aware of one study that had ex-
amined joint kinetics and kinematics during uphill
cycling (Caldwell, Hagberg, McCole, & Li, 1999).
In their study, Caldwell et al. (1999) reported
that 8% uphill cycling showed a signicant increase
in the magnitude of the peak ankle plantarexor
Table 2. A review of studies on pedal and crank kinetics during uphill cycling
Publication Cyclists Slope Findings
Caldwell et al. (1998) 8 elite cyclists 8%
Overall patterns of pedal and crank kinetics were similar between level
and 8% uphill cycling in a seated position. Higher peak pedal force, shift
of crank torque to later in the crank cycle. A modified pedal orientation
was observed during seated and standing uphill cycling.
Bertucci et al. (2005) 7 male cyclists 9.25%
The torque was 26% higher at a 45° crank angle in a seated uphill
situation compared to level terrain. At lower cadences, during uphill
cycling the peak torque value was significantly (42%) higher compared
to higher cadences during level terrain cycling.
Alvarez and Vinyolas
(1996) 1 male cyclist 8-9%
No visual differences between level terrain and seated uphill cycling.
More drastic ally increased pedal forces were observed during standing
uphill cycling.
Kinesiology 44(2012) 1:5-17Fonda, B. and Šarabon, N.: BIOMECHANICS AND ENERGETICS OF UPHILL ...
10
(25%) and knee extensor (15%) moments, and a
shift of these peak moments to earlier in the crank
cycle (12° and 15°, respectively). During standing
uphill cycling, the ankle plantar exor moment in-
creased by 160% and was shifted forwards by 45°
in the crank cycle, when compared to the uphill
seated position. The knee extensor prole showed
an extended bimodal prole with a shift towards
the late down stroke period, although the peak mo-
ment occurred slightly earlier (3°). The knee exor
moment in the two seated conditions (uphill and
level) showed a signicant increase compared to
standing uphill cycling. The patterns for the hip
joint showed the most similarities across all condi-
tions with only signicant alterations in the peak
extensor moment during seated uphill conditions,
as compared to standing uphill conditions.
Changes during uphill standing conditions are
related to the removal of the saddle as a base of
support for the cyclist. As a consequence, there are
higher forces on the pedals, the forward shift in
pedal orientation, and the more forward hip and
knee position (Caldwell, et al., 1998). The transi-
tion from a seated to a standing position provokes
large changes to the range of motion of the joints of
the lower limbs. According to Shemmell and Neal
(1998), the range of motion at the knee during stand-
ing uphill cycling (28.7±8.8°) decreased signicant-
ly from that of a seated position (73.0±6.4°). This
signicant change could be primarily attributed
to the forward translation of the body in relation
with the bicycle and also by the fact that some de-
gree of bicycle tilt is introduced into the movement.
Changes to the position of the body also appear to
affect the range of motion in the other joints of the
lower limbs. The range of motion at the hip joint
(68.8±6.7°) is increased from the sitting position
(42.8±4.9°) and the range of motion for the ankle
joint (40.5±6°) is increased from that of the seated
position (25.7±14.1°).
Although only slight and non-signicant
changes in pedal forces were present during seated
uphill cycling, an increase in the peak pedal force
during standing uphill cycling seems to be related
to the removal of saddle support with which the
body weight increases the force production. The
forward translation of the body in relation to the
bicycle provokes a smaller range of motion in the
knee, which conrms the previous hypotheses that
more work is done by using body weight.
Neuromuscular aspect of uphill
cycling
Neuromuscular aspects in cycling have been
studied extensively (Dorel, Couturier, & Hug, 2008;
Ericson, et al., 1985; Hug & Dorel, 2009; Hug, et al.,
2008). Studies have examined the neuromuscular
activation and adaptation of the cycling movement
by observing the timing and intensity of muscular
activity using surface electromyography (EMG) (for
a review see Hug and Dorel, 2009).
The timing and the intensity of muscular ac-
tivity can be altered when changing the seat height
(Ericson, et al., 1985; Sanderson & Amoroso, 2009),
power output (Ericson, et al., 1985; Suzuki, Watan-
abe, & Homma, 1982), pedaling technique (Can-
non, Kolkhorst, & Cipriani, 2007), cadence (Nep-
tune, Kautz, & Hull, 1997) and/or posture (Savel-
berg, Van de Port, & Willems, 2003). Changing the
body posture either by changing the bicycle setup
(geometry settings) or by adapting the posture due
to the terrain characteristics (e.g. during uphill cy-
cling) can alter the angle/torque relationship of the
involved muscles (Hof, 2002; Lunnen, Yack, & Le-
Veau, 1981) and therefore, potentially affect neu-
romuscular patterns in the lower extremities.
Despite the relatively wide body of knowledge
concerning neuromuscular activation when cycling
on a level surface, there are only a few published
reports on the effects of uphill cycling (Li & Cald-
well, 1998; Clarys, Alewaeters, & Zinzen, 2001;
Duc, Bertucci, Pernin, & Grappe, 2008; Fonda &
Sarabon, 2010b; Fonda, et al., 2011; Sarabon, et al.,
2011). The ndings from the published studies are
presented in Table 3.
Seated uphill cycling
Sarabon et al. (2011) and Fonda et al. (2011)
reported changes in muscle activity patterns during
steep uphill conditions (20%). The majority of
changes were observed in muscles that cross the hip
joint, as well as the m. tibialis anterior. Signicant
changes in muscle activation timing during 20%
uphill cycling, when compared to level terrain, were
observed in the m. rectus femoris (15° later onset
and 39° earlier offset). The range of activity during
20% uphill cycling compared to level terrain was
also signicantly modied in m. vastus medialis,
m. vastus lateralis (8° and 5° shorter, respectively)
and m. biceps femoris (17° longer). Furthermore, a
reduction of the EMG activity level was observed
for m. rectus femoris and m. tibialis anterior during
20% uphill cycling compared to a level terrain (25%
and 19%, respectively), while the opposite effect
was observed for m. gluteus maximus (12%). No
signicant changes were observed during 10%
uphill cycling compared to level terrain.
The absence of changes in muscles` activation
patterns during uphill cycling on moderate slopes
(up to 10%) appears to be consistent among dif-
ferent studies. Specically, Duc et al. (2008) and
Li and Caldwell (1998) found no signicant differ-
ences in the intensity and timing of muscle activ-
ity patterns for individual muscles during seated
uphill cycling compared with level terrain cycling.
Conversely, Clarys et al. (2001) reported that global
integrated EMG (the average of the four monitored
Fonda, B. and Šarabon, N.: BIOMECHANICS AND ENERGETICS OF UPHILL ... Kinesiology 44(2012) 1:5-17
11
Publication Cyclists Slope Findings
Li and Caldwell
(1998)
10 healthy
students 8%
The muscle activities of GC and BF did not exhibit any profound differences
among varying conditions. Overall, the change of cycling grade alone
from 0 to 8% did not induce a significant change in neuromuscular
coordination. The postural change from seated to standing pedaling at
an 8% uphill grade was accompanied by the increased and/or prolonged
muscle activity of hip and knee extensors.
Clarys et al. (2001) 12 professional
road cyclists 12%
Regardless of the position of the pelvis, the muscular intensity of lower
limb muscles increased with increasing slope inclination, while the
muscular intensity of the arms decreased with the same increasing
slope inclination. In addition, the decreased intensity of the arm muscles
remained significantly higher with the saddle fully for ward.
Duc et al. (2008) 10 trained
cyclists
4, 7 and
10%
No changes noted in muscle activity patterns during seated uphill
cycling at any slope for any of the muscles. Standing uphill cycling had
a significant effect on the intensity and duration. GM, VM, RF, BF, BB, TA,
RA and ES activity were greater in standing while SM activity showed a
slight decrease. When standing, the global activity of the upper limbs was
higher when the hand grip position was changed from brake level to the
drops, but lower when the lateral sways of the bicycle were constrained.
Fonda et al. (2011)
12 trained
mountain
bikers
20 % Modified timing and intensity of activity of the RF, BF and GM during a
20% slope.
Sarabon et al. (2011)
12 trained
mountain
bikers
10 and
20%
Altered body orientation during a 20% slope, but not a moderate slope
of 10%, significantly modif ied the timing and intensity of several lower
extremity muscles, the most affected being muscles that cross the hip
joint and TA.
Table 3. A review of studies on neuromuscular activit y during uphill cycling
Legend: GC, gastrocnemius; BF, biceps femoris, GM, gluteus maximus; VM, vastus medialis; RF, rectus femoris; BB, biceps
brachi; TA, tibialis anterior; RA, rectus abdominus; ES, erector spinae.
muscles) of the lower extremity muscles increased
with the increasing slope. However, these authors
did not study the timing or intensity of the activ-
ity of individual lower extremity muscles. Hence,
their results are difcult to compare with the re-
sults reported by Li and Caldwell (1998), Duc et al.
(2008) and Sarabon et al. (2011). To the best of our
knowledge, until now only the studies by Fonda et
al. (2011) and Sarabon et al. (2011) were conduct-
ed during steep uphill cycling. This is surprising,
given that slopes around 20% are frequently met
by mountain bikers (and less frequently by road
cyclists) during races or training sessions.
Standing uphill cycling
During standing uphill cycling, signicant neu-
romuscular modications are to be expected, since
there is a signicant change in body posture and
muscle coordination, especially involving increased
activity of the muscles in the upper extremities. Duc
et al. (2008) found signicant alterations in intensity
and timing on m. gluteus maximus, m. vastus medi-
alis, m. rectus femoris, m. biceps femoris, m. biceps
brachii, m. triceps brachii, m. rectus abdominis, m.
erector spinae and m. semimembranosus during
standing uphill cycling. They reported that only the
muscles crossing the ankle remained unchanged.
Among all the muscles tested, arm and trunk mus-
cles exhibited the most signicant increase in activ-
ity. The peak EMG activity of m. gluteus maximus,
m. vastus medialis, m. biceps femoris, m. gastroc-
nemius and m. soleus shifted later in crank cycle,
while the timing of the other monitored muscles
remained unchanged. Similarly, Li and Caldwell
(1998) reported an increase in the EMG activity
of m. gluteus maximus, m. rectus femoris and m.
tibialis anterior and prolonged burst duration of m.
gluteus maximus, m. vastus medialis and m. rectus
femoris during standing uphill cycling when com-
pared to the seated position. The EMG activity of
m. biceps femoris and m. gastrocnemius did not
display signicant alterations during standing up-
hill cycling. In contrast to Duc, et al. (2008), altera-
tions were also found in m. tibialis anterior, while
no differences were observed in m. biceps femoris.
The cause for the differences between the studies
could be the measurement equipment used. Duc et
al. (2008) used the motorized treadmill, while Li
and Caldwell (1998) performed the tests on a sta-
tionary bicycle ergometer.
The results seem to be related to the increase
of the peak pedal force, the change of the hip and
knee joint moments, the need to stabilize the pelvis
in reference with removing the saddle support, and
the forward shift of the center of mass.
Kinesiology 44(2012) 1:5-17Fonda, B. and Šarabon, N.: BIOMECHANICS AND ENERGETICS OF UPHILL ...
12
Performance and comfort optimization
during uphill cycling
Body position
The effect of the body position has already been
partly discussed in the section “Equations of uphill
cycling”. Welbergen and Clijsen (1990) conducted
a study where they examined the effect of body
position (upright and racing position) on maximal
power and oxygen consumption. They concluded
that the trunk angle had a signicant effect on the
maximal power output delivery in a 3-minute test,
with the highest amount of power produced in the
upright position. Based on that data, they estimated
that if a cyclist’s maximal power is assumed to be
20% lower in a racing position, the incline at which
the cyclist would benet by being in the upright po-
sition is approximately 7.5%. At this point, by ne-
glecting wind speed, air resistance is no longer the
most limiting factor.
The standing position is often employed during
uphill cycling, especially at lower cadences. It has
been reported that oxygen consumption is lower
during uphill cycling in a seated compared with a
standing position at around 45% of maximal oxy-
gen consumption. This indicates that performance
during uphill cycling at such a low intensity is op-
timized by using the seated rather than the stand-
ing position (Ryschon & Stray-Gundersen, 1991).
Knowing more about which position favours per-
formance for more intense cycling would be help-
ful for cyclists and their coaches. Therefore, Hansen
and Waldeland (2008) conducted a study to examine
the transition from the seated to the standing posi-
tion. Their results showed that cycling in a stand-
ing position resulted in a signicantly better per-
formance than seated cycling at the highest power
output (around 165% of maximal aerobic power)
while the seated-to-standing transition was identi-
ed at 94% of maximal aerobic power. Below this
intensity, seated cycling is energetically more eco-
nomical than standing.
Saddle position
When considering health-related issues during
cycling, lower back pain is certainly among the most
common issues (Marsden & Schwellnus, 2010). In
their uoroscopic/biomechanical and clinical study,
Salai et al. (1999) showed that tilting the saddle
forward by 10 to 15° can signicantly decrease the
tensile forces on lumbar vertebrae and therefore
reduce lower back pain during cycling. Based on
their research, we can assume that lower back
pain could become even worse if cyclists adjust
their posture due to uphill terrain characteristics
(increased tensile forces on lumbar vertebrae).
During uphill cycling, especially on steeper slopes,
cyclists need to prevent themselves from sliding off
the saddle and have to ensure that they keep a stable
and balanced position. Additionally, by leaning
and moving forward, the area on which the cyclist
sits is reduced. Therefore, the saddle loses all its
ergonomic characteristics and provokes discomfort.
It would be benecial for their comfort if cyclists
would tilt the saddle forward, thus allowing for the
anterior rotation of the pelvis, which helps keep the
lumbar lordosis during cycling and subsequently
decreases the tensile forces on the lumbar vertebrae.
By tilting the saddle, the level of support on which
cyclists sit would also increase.
In a study by Fonda et al. (2011), a novel bicycle
geometry optimization was used with the goal of
enhancing the performance and comfort of cycling
during uphill conditions. With an adjusted tilt and
the longitudinal position of the saddle they wanted
to bring the posture during uphill cycling closer to
the posture acquired during level terrain cycling
and achieve a more comfortable position (Figure 3).
The use of the adjusted saddle position during a
20% slope counteracted the neuromuscular changes,
suggesting that the applied adjustment of the tilt and
therefore the position of the saddle was successful
in bringing the posture during uphill cycling closer
to that of the posture during level terrain cycling.
Specically, neither the timing nor the intensity
of the activity of the studied muscles differed
between 20% uphill cycling with an adjusted saddle
position and level terrain cycling. The exceptions
concerned the onset of m. vastus medialis and offset
of m. biceps femoris, where statistically signicant
changes were observed during 20% uphill cycling
with an adjusted saddle position versus level terrain
cycling. However, these changes were rather small
(1.5-6%), and probably not practically relevant.
Another interesting nding was that the use of an
adjusted saddle position during 20% uphill cycling
was positively perceived by all the participating
cyclists in terms of both their comfort and their
performance. These results could have practical
relevance in terms of improving performance during
uphill cycling, as well as reducing the prevalence of
lower back pain associated with cycling. Based on
pilot studies (S2P, Ltd., personal communication),
the adjusted saddle position was found to be
transformative in reducing oxygen consumption
(6%) and therefore increasing the economy of uphill
cycling. That was later conrmed by a reduction
(30-60% decrease) of muscle activity in the upper
extremities (m. brachioradialis). Both parameters
were measured during 20% uphill cycling in
laboratory conditions. Nevertheless, the adjusted
saddle position requires further investigation,
especially in outdoor conditions.
The use of an adjusted saddle position during
20% uphill cycling counteracted the changes in
muscular activity, suggesting that the adjusted sad-
dle could be successful in bringing the posture dur-
ing uphill cycling closer to that of the level terrain.
Fonda, B. and Šarabon, N.: BIOMECHANICS AND ENERGETICS OF UPHILL ... Kinesiology 44(2012) 1:5-17
13
Further directions for research
Current studies are limited either to laborato-
ry conditions or small to moderate slopes. Future
biomechanical and physiological studies should be
focused on outdoor conditions and steeper slopes.
Due to the technical difculties of measuring pedal
forces without substantially affecting pedaling by
abnormal pedal (weight, size, wires, etc.), one goal
should be the development of a force pedal that does
not alter the pedaling technique. Another limitation
of the outdoor studies is the kinematical evaluation
in measuring joint forces and movement. Different
measurement equipment should therefore be used
for evaluating joint movements.
Steeper slopes are common in mountain bike
races, as well as in road racing. The majority of
studies presented in this review were conducted on
slopes of up to 12%. Further studies should also fo-
cus on steeper slopes (20%) in comparison to level
terrain cycling.
Understanding motor behavior and physiological
responses in such conditions will allow scientists
to transfer knowledge into practice and enhance
performance, comfort and safety during cycling.
Since the large majority of races are won in the hilly
sections of the race, scientists should also focus on
bicycle geometry optimization specically for these
conditions (i.e. “bike-tting”) instead of for only
“standardized” level terrain conditions.
Conclusions
Unlike level ground cycling, where wind resist-
ance is a major opposing force, uphill cycling re-
quires a great portion of power to overcome grav-
ity. Posture during uphill cycling differs compared
to level terrain as aerodynamics no longer play a
crucial role as the main opposing force. In windless
conditions, with a slope that is 7.5% or steeper, it is
more economical to adopt an upright posture rather
than just a normal posture with hands on the drops.
The inclination of the terrain forces cyclists to ad-
just their posture to maintain a stable position and
to increase their mechanical output. To accomplish
this, cyclists usually shift forward on the saddle
and ex the trunk (leaning forward). Seated uphill
cycling does not appear to be a factor that inuences
cycling efciency, pedal forces and joint dynamics,
while the neuromuscular patterns are altered.
Sometimes, cyclists stand on the pedals to in-
crease their mechanical output. Changing the pos-
ture by standing alters some of the characteristics
of locomotion, such as economy and efciency, kin-
ematics and kinetics, and neuromuscular activa-
tion patterns. Increased ventilation during stand-
ing uphill cycling is accompanied by an increase
in breathing frequency, which seems to be related
to the rhythmic pattern of pedaling. Additionally,
the forward translation of the body in relation to
the bicycle provokes a smaller range of motion in
the knee. Changes in muscle activity during stand-
ing uphill cycling seem to be related to the increase
of the peak pedal force, the change of the hip and
knee joint moments, the need to stabilize the pelvis
in reference with removing saddle support, and a
forward shift in the center of mass.
Figure 3. An adjustable saddle position, which enables the
cyclists to adjust the angle and position of the saddle by
putting it into three different positions: (1) horizontal position
(normal), (2) 10% angle of the saddle and (3) 20% angle of
the saddle. Note that the forward movement of the saddle
and optimized saddle angle does not alter the saddle height.
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Submitted: March 18, 2012
Accepted: May 15, 2012
Correspondence to:
Nejc Šarabon, Ph.D.
University of Primorska, Science and Research Centre
Institute for Kinesiology Research
Garibaldijeva 1, 6000 Koper, Slovenia
Phone: +386 40 429 505
E-mail: nejc.sarabon@zrs.upr.si
Fonda, B. and Šarabon, N.: BIOMECHANICS AND ENERGETICS OF UPHILL ... Kinesiology 44(2012) 1:5-17
17
Pobjednici najvećih biciklističkih 3-tjednih eta-
pnih utrka (npr. Giro d’Italia, Tour de France, Vuel-
ta a Espana) su najčešće biciklisti koji dominiraju u
segmentima utrke s usponima. Amaterski biciklisti,
pak, često izbjegavaju uzbrdice zbog neugodnosti
koju vožnja uzbrdo izaziva. Zbog toga je nužno po-
znavati i razumjeti kretanje tijekom vožnje bicikla
uzbrdo da bi se izabralo optimalno motoričko pona-
šanje koje se može primijeniti u praksi. Cilj je ovoga
rada ocijeniti kvalitetu istraživanja o biomehanici i
energetskim zahtjevima bicikliranja uzbrdo. Ukupno
smo analizirali 40 članaka iz znanstvenih i stručnih
časopisa koji su istražili energetiku, sile pedaliranja
i sile u zglobovima, ekonomičnost i učinkovitost mi-
šićne aktivnosti te optimizaciju izvedbe i udobnosti
tijekom vožnje bicikla uzbrdo. Za vožnje po uzbrdici
biciklisti moraju svladati gravitaciju, a da bi u tome
BIOMEHANIKA I ENERGETIKA VOŽNJE
BICIKLA UZBRDO: PREGLED ISTRAŽIVANJA
uspjeli, potrebne su određene promjene u položa-
ju tijela. Glavni rezultat ovog preglednog rada jest
zaključak da se mišićna aktivnost mijenja tijekom
vožnje bicikla uzbrdo u sjedu usporedbi s vožnjom
po ravnom terenu, dok se s druge strane, sile na
pedalama, dinamika zglobova i učinkovitost vožnje
ne mijenjaju značajno. Suprotno tome, tijekom vo-
žnje bicikla uzbrdo u stojećem položaju sve ranije
spomenute mjere su različite od onih zabilježenih u
vožnji bicikla uzbrdo u sjedu ili u vožnji po ravnom
terenu. Daljnja istraživanja trebala bi se usmjeriti
na istraživanja provedena u vanjskim uvjetima i na
strmijim usponima.
Ključne riječi: uspješnost, učinkovitost, bio-
mehanika, fiziologija, optimizacija
