The purpose of this investigation was to determine whether changes in CAL resulted in significant changes in joint angles, and how these changes are related to changes in cycling performance

Too, Danny

Williams, Christopher D.

English

The College at Brockport, State University of New York: Digital Commons @Brockport

THE EFFECT OF PEDAL CRANK ARM LENGTH ON LOWER LIMB JOINT ANGLES IN AN 
UPRIGHT CYLING POSITION 
 
Danny Too and Chris Williams 
 
The College at Brockport, NY, USA 
email:  dtoo@brockport.edu,  web: www.brockport.edu 
 
 
INTRODUCTION 
 
Previous investigations reported that changes in 
crank arm length (CAL) from 110-265 mm (i.e,, 
110, 145, 180, 230, and 265 mm) resulted in 
significant differences in power production and 
cycling duration (but not necessarily with adjacent 
CAL {i.e., 110 vs. 145 vs. 180 vs. 230 vs. 265 
mm}) [1,2,3,4].  However, there was no information 
provided whether changes in CAL also resulted in 
significant changes in joint angles, and how changes 
in joint angle may affect cycling performance 
(based on muscle force-length relationships).  
Therefore, the purpose of this investigation was to 
determine whether changes in CAL resulted in 
significant changes in joint angles, and how these 
changes are related to changes in cycling 
performance. 
 
METHODS 
 
Seventeen males participants age 23 ± 6.74 years 
(mean ± SD) were each tested on a free weight 
Monark cycle ergometer (Model 814E) at five pedal 
CAL (110, 145, 180, 215 and 250 mm) using an 
adjustable pedal shaft mechanism (RangeMaker™).  
CAL sequence was randomly determined, and seat 
height was set at 100% of leg length.  Each 
participant pedaled (with pedal toe-clips) at 60 rpm 
(in cadence to a metronome) with a 3 kg mass 
applied to the ergometer.  Hip, knee and ankle 
angles (i.e., minimum [Min], maximum [Max], and 
range of motion [ROM]) were recorded for 10 
seconds from the right sides of the body using 3 
electrogoniometers (SG150 and SG100 sensors with 
a K100 amplifier by Biometrics Ltd) connected to a 
4 channel analog amplifier.  The signal was routed 
to an A/D box (Noraxon NorBNC), a synchronizing 
unit, and to a laptop computer. 
 
RESULTS 
 
Nine repeated measures ANOVAs were performed 
to determine if there were significant differences (p 
< 0.01) in the Min, Max, and ROM of the hip, knee, 
and ankle.  Results indicated a significant change in 
the Min joint angle and ROM of the hip, knee, and 
ankle with 35 mm increments in CAL from 110-250 
mm (see Table 1).  The following trends were found 
with incrementing CAL: (1) decreasing Min hip and 
knee angle; (2) increasing Min ankle angle (see Fig 
1), (3) increasing ROM of the hip and knee, (4) 
decreasing ankle angle ROM (see Fig 2) and (5) no 
apparent trends in the Max hip, knee, and ankle 
angle (see Fig 3).  Significant post-hoc tests (p < 
0.05) revealed: (1) decrements in the Min hip and 
knee angle for each 35 mm increment in CAL; (2) 
increments in the hip and knee ROM for each 35 
mm increment in CAL; (3) increments in the Min 
ankle angle between the 145 mm and 180 mm CAL; 
and (4) decrements in the ankle angle ROM 
between the 110 mm and 145 mm CAL, and 
between the 145 mm and 180 mm CAL. 
 
DISCUSSION 
 
It was expected that increments in CAL would 
result in decrements in Min joint angles, and 
increments in joint ROM (if the seat height was 
controlled).  However, the reverse was found for the 
ankle angle (i.e., increment in Min and decrement in 
ROM) with increments in CAL.  This unexpected 
trend, in conjunction with a significant increment in 
the Min ankle angle between the 145 mm and 180 
mm CAL (from 87.8 deg [i.e., a dorsiflexed 
position] to 91.5 degrees [i.e., a plantar flexed 
position]) may be attributed to: (1) insufficient 
flexibility of the ankle and/or physical 
constraints/limitations to dorsiflex (due to the 
structure of the ankle joint) as the CAL is increased; 
(2) greater ankle force production potential (in a 
more effective portion/range of the force-length 
curve) as the Min ankle joint angle increases (from 
a dorsiflexed position to a plantar flexed one); and 
(3) increased ankle joint angles to a plantar flexed 
position (with longer CALs) which alters the joint 
angles to allow the larger hip and knee muscles to 
more effectively produce force (i.e., changes the 
length of the hip and knee muscles so it is in a more 
effective portion of the tension-length curve to 
produce force).  This appears to be supported by the 
result that a systematic increase of 35 mm in CAL 
from 110-250 mm did not result in an equivalent 
systematic decrease in Min knee angle.  In fact, with 
each change in CAL by 35 mm (from 110 to 145 to 
180 to 215 to 250 mm), the minimum knee angle 
decreased 14.5, 13.3, 11.1, and 7.3 degrees, 
respectively.  Further investigations in this area are 
required to understand the relationship between 
CAL, joint angles, muscle length, force/torque 
production and cycling performance. 
 
 
Figure 1:  Minimum hip, knee, and ankle angles 
with changes in pedal crank arm length 
 
Figure 2:  Hip, knee, and ankle range of motion 
with changes in pedal crank arm length 
 
 
Figure 3:  Maximum hip, knee, and ankle angles 
with changes in pedal crank arm length 
 
REFERENCES 
 
1. Too D, et al. J Spt Sci 18, 153-161, 2000.  
2. Too D, et al. Human Power 51, 3-6, 2000.   
3. Too D, et al. Proceedings of NACOB’98, Waterloo, 
Ontario, CANADA, 1998.  
4. Too D, et al. ISB’99 Book of Abstracts, Calgary, 
Alberta, CANADA, 1999. 
 
 
Table 1.  Main Effect of Hip, Knee, and Ankle Joint Angles at Five Crank Arm Lengths (*p < 0.01) 
       Crank Arm Length (mm)     
Angle (deg)  Mean (SE) 110 145 180 215 250 
  *Min 121.8 (3.43) 111.0 (3.97) 101.7 (4.68) 91.8 (5.67) 86.9 (6.29) 
Hip    Max 160.9 (2.09) 162.4 (2.42) 164.3 (2.17) 161.5 (2.67) 164.7 (2.64) 
  *ROM 37.9 (3.61) 50.5 (2.95) 61.4 (4.22) 69.0 (4.81) 77.4 (5.63) 
  *Min 102.2 (4.34) 87.7 (4.78) 74.4 (4.93) 63.6 (5..22) 56.3 (5.66) 
Knee    Max 157.2 (3.84) 153.5 (3.69) 151.4 (5.41) 147.6 (5.68) 147.9 (6.95) 
  *ROM 55.0 (4.28) 65.8 (4.3) 77.1 (5.73) 84.0 (5.94) 91.5 (6.62) 
  *Min 84.3 (2.47) 87.8 (2.13) 91.5 (2.58) 93.2 (2.67) 93.9 (2.47) 
Ankle    Max 117.2 (3.51) 115.4 (3.62) 115.9 (3.78) 116.8 (3.12) 118.3 (3.71) 
  *ROM 32.9 (3.8) 27.5 (3.16) 24.3 (2.76) 23.6 (2.52) 24.4 (2.7) 
 


The Effect of Pedal Crank Arm Length on Lower Limb Joint Angles in an Upright Cycling Position

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The Effect of Pedal Crank Arm Length on Lower Limb Joint Angles in an Upright Cycling Position

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