Bicycling Injuries



Bicycling Injuries


Chad A. Asplund



INTRODUCTION



  • Participation in bicycling is rapidly growing.



    • In 2009, 38.1 million Americans age 7 and older were estimated to have ridden a bicycle six times or more (22).


  • There are many different ways to participate in bicycling: road cycling, mountain biking, touring/commuting, cyclocross, and BMX.


  • With the increased participation, there has been an increase in both traumatic and overuse injuries:



    • Each year, more than 500,000 people in the United States are treated in emergency departments and more than 700 people die as a result of bicycle-related injuries (10).


  • Most common areas for overuse injuries in bicycling are the knee, neck, and back (3,4).


  • Many of these overuse injuries occur secondary to improper bicycle fit or to training errors.


  • This chapter will outline the different ways people can participate in bicycling, the anatomy and fit of the bicycle, injury epidemiology, traumatic and overuse injuries, cycling-related equipment, and common training errors.


DIFFERENT MODES OF BICYCLING


Road Cycling



  • Road racing: Open road 25-100 miles.


  • Criterium: Multiple laps around a short course.



    • Very popular in America


    • High potential for crashing/injury


  • Time trial: Race against the clock with wave start with 1-5 minutes between riders.


Mountain Biking



  • Cross-country: Longer races over variable terrain.


  • Downhill: Steep downhill race where focus is on speed; injuries occur as safety is sacrificed for speed.


  • Dual slalom: Two racers compete in downhill ski-style slalom course.


Touring/Commuting



  • Long-distance road riding for recreation. Rider may be carrying panniers/saddlebags.


Cyclocross



  • Off-road race on road-style bike, in which riders complete multiple short (1-2 mile) loops in a set time period. Obstacles require rider to dismount, remount, and carry bicycle over the course.


BMX/Trick Cycling



  • Riders compete against other riders over dirt courses of varied terrain or individually on ramps with stairs and railings, with aerial stunts. There is a high risk for injury with aerial acrobatics.



    • Fastest growing segment of U.S. cycling with 60,000 riders (14).


    • Largest portion of child and adolescent cyclists.


BICYCLE ANATOMY



  • Although there are many different modes of bicycling, the general anatomy of the bicycle is similar (Fig. 88.1).


Frame Types



  • Standard road: Traditional upright geometry with top tube parallel to ground.


  • Compact road: Sloping top tube allows rider to fit smaller frame; this maximizes stiffness and minimizes weight.


  • Mountain/hybrid: Flatter geometry, heavier bicycle, may have front and/or rear suspension to absorb shock.


Fit



  • Most important attribute in the evaluation of overuse bicycling injuries.


  • Bicycle fit may be done at local bike shop with bicycle purchase or available for a fee.


  • Fit Kit and Serotta “Size Cycle” have been used (11).







    Figure 88.1: Bicycle anatomy.


  • Best frame size for cyclist is as small vertically as possible with enough length horizontally to allow a stretched out relaxed upper body. This frame will be lighter and stiffer and handle better (12).


Frame Size



  • Most important attribute for appropriate frame size is top tube length.


Top Tube Length



  • The ideal position varies here more than anywhere else for cyclists, depending on riding style, flexibility, body proportions, and frame geometry, among others.


  • Upper body position may change as riding style evolves.


  • May be measured by placing the elbow at the fore end of the saddle; outstretched fingers should touch the handlebars.


  • May also have rider, while in the drops, look straight down; the hub of the front wheel should be obscured by the handlebar.


Seat Height



  • Optimal saddle height has been estimated based on maximal power output and caloric expenditure (9).


  • Calculate height, which will be within a centimeter of 0.883 × inseam length, measured from the center of the bottom bracket to the low point of the top of the saddle. This allows full leg extension, with a slight bend in the leg at the bottom of the pedal stroke.


  • When seated on the bike with the pedal at the 6 o’clock position, there should be 20-25 degrees of flexion of the knee.


  • Alternatively, the seat may be raised until the hips start rocking when pedaling and then the seat is lowered until the rocking disappears.


Saddle Position



  • Check the position of the forward knee relative to the pedal spindle; for a neutral knee position, you’ll be able to drop a plumb line from the tibial tubercle and have it bisect the pedal spindle (knee over pedal spindle [KOPS] position) (9).


Handlebar Position



  • Most cyclists select a bar that is just as wide as their shoulders.



    • A wider bar opens the chest for better breathing and more leverage but sacrifices aerodynamics.


    • A narrower bar increases aerodynamics but sacrifices stability.


  • Handlebar height should be at or below the saddle height; how far below depends on the flexibility and experience of the cyclist.


Crank Arm Length



  • Length is based on size and riding style. Shorter crank arm length is better for quick acceleration. Long crank arms are better for pushing larger gears at a lower cadence (12).


  • To minimize oxygen consumption, crank arm length is dependent on femur length.



  • 2.33 × femur length + 55.8 cm (28). This roughly translates to:



    • Frame size < 54 cm: 170-cm crank arm


    • Frame size 55-61 cm: 172.5-cm crank arm


    • Frame size > 61 cm: 175-cm crank arm


Gearing



  • Chain wheels: Large chain ring (usually 53 teeth) and small chain ring (usually 39 teeth) 53/39; recently, a more compact 50/34 chain ring combination has become more popular to allow riders to climb hills and spin at higher cadence.


  • Cassette: Cluster of gears (cogs) mounted to right of rear wheel.


  • Gear ratio: Number of teeth on chain ring divided by number of teeth on selected cog.


  • Higher ratio requires more strength, endurance, and technique.


  • Lower gear ratio allows for more spinning and higher cadence; without proper technique will yield less power.


Cadence



  • Optimal cadence determined by type of race (time trial, climbing, criterium), body type, muscle fiber type, and training level (8).


  • Higher cadences put less strain on trained leg muscles.


  • Low cadences increase intramuscular pressure, reducing blood flow to the muscles during the power phase of the pedal stroke.


  • High-cadence/low-resistance training reduces the incidence of overuse injuries. Cyclists beginning a season or returning from injury should return with this type of training.


  • Cadence is individual and should be determined on a rider-by-rider basis.


INJURIES


Epidemiology

May 22, 2016 | Posted by in SPORT MEDICINE | Comments Off on Bicycling Injuries
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