March, 2010

Crank Arm Length: What you should know.

March 29, 2010

Knee angle via video analysis

Knee angle via video analysis

When getting a bike fit or buying a new bike, the crank arm length can often be overlooked. There are general guidelines based on inseam, height, and/or bike size. Such guidelines may look like this:
  • Under 5'10 use 170mm cranks for general (road) racing and training
  • 5'10 to 6'1 use 172.5mm cranks
  • 6'1 plus use 175mm cranks
Or some people like to be a little more scientific by using this formula:

Crank arm length (mm)= inseam (inches) x 5.48

Well, there's a lot of information or misinformation out there on crank arms, cycling efficiency, power output, and knee injuries.

An argument for a longer crank arm is better torque in the pedal stroke especially with climbing and sprinting. An argument for a shorter crank arm is the ability to spin more efficiently and thus is used for cyclists with a high cadence. Another argument for a shorter crank arm is to reduce knee injuries since a longer crank arm will cause greater knee flexion at top dead center, or at the top of the pedal stroke.

Here's my take:  for most of us, we can adapt to a crank arm length one size above and one size below the "suggested" length based on the guidelines above and our cycling mechanics.  However, for anyone with hip, knee, and low back pain, it may be more important to do a little trial and error on selecting the crank arm length.

One key piece to look at that is often overlooked is hip flexibility.  When performing a bike fit and cycling analysis, I am particularly interested in a cyclist's hip mobility, especially in hip flexion or knee to chest and then internal and external rotation as well as hamstring length and lumbar spine flexion.  Furthermore, we check these in all combinations since the cyclist will flex forward more going uphill, lengthening the lumbar spine and hamstrings while bringing the knee to chest.  If a cyclist has reduced hip mobility, especially in flexion and internal rotation, then crank arm length may become a significant factor in reducing the risk of injury and optimizing performance.

Consider someone with a tight hip on the right side.  If the crank arm length is too long, the rider will not have enough hip flexion at top dead center (TDC) and thus will either have the knee veer out laterally on the upstroke (the ever popular figure 8 stroke) or he/she will rock the pelvis to the left and hike up the right side to make more room for the knee coming towards the chest.  Both of these accommodations or compensations can cause back, hip, or knee pain on EITHER leg or back.

Example of Dynamic Functional Analysis

Example of Dynamic Functional Analysis

For this reason, we typically do a flexibility, mobility, stability, and dynamic functional biomechanics examination to fit the bike to you and YOU to the bike.  Fitting you to the bike is as important to adjusting the bike to your body.  Any imbalance found in the functional exam can hinder performance and cause injury, despite the best bike fit.

To learn more about our bike fit and cycling analysis, visit us at www.innersport.com or click here.
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Dr. Jess to host functional stretching clinic for ALC

March 29, 2010

Psoas Functional Stretching

Psoas Functional Stretching

As a supporter and two time Sports Medicine Tent volunteer for the Aids Lifecycle since 2003, Dr. Jess Greaux will be hosting a functional stretching clinic for cyclists at Innersport.
  • What: Functional Stretching Clinic for Cyclists
  • Where: Innersport Performance Therapy Clinic
  • When: April 14th, 7:30 sharp.
  • Wear: workout clothes
  • Why: Injury prevention and Optimize Performance
  • RSVP is mandatory
Dr. Jessica Greaux, DC, ART has been an avid supporter of ALC since 2003 when she first volunteered in the Sports Medicine Tent on the ride. Ever since then, she has been active in helping ALC cyclists complete the event injury-free. Not only has she given numerous clinics at Sports Basement and Innersport, she has co-authored an Injury Prevention Manual specifically for ALC. Dr. Greaux has worked with Stephen Cadby and Ride Leaders to find tools to enhance the experience of ALC riders ON and BEFORE the ride by introducing the importance of foam rollers in the sports med tent as well as review bike biomechanics and core strengthening techniques. Please join Dr. Greaux on April 14th at Innersport to learn which stretches to do when for what purpose and then how. There is a lot of controversy on stretching in the media and in the research, however there are a few things we do know. Dr. Greaux's stretching routine and techniques are based on current research and clinical experience and is guaranteed to be relatively new to the cyclist. Please RSVP by clicking here. Dr. Greaux's Cycling Care:
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Strength Training for Cyclists

March 20, 2010

Dr. Jess at Hell's Angels (Els Angels) Monastery in Girona, Spain

Dr. Jess at Hell's Angels (Els Angels) Monastery in Girona, Spain

Since I am on a cycling vacation myself and do not have the resources to write my own blog, I thought I'd share with you another interesting article by Dr. Mirkin, with his permission. Enjoy!

Dear Dr. Mirkin: Will lower-body weight training make me a better cyclist?

A study from Cowan University in Joondalup, Australia shows that adding resistance leg weight training does not help competitive bicycle racers to race faster (Journal of Strength and Conditioning Research, November 2009). The cyclists were divided into two groups: one that continued their bicycling training, while the other group did the same cycling training but added a six-week undulating, periodized resistance training program (3/wk). Before and after the six-week training period, the cyclists completed a maximal graded exercise test, a 30-km dynamic cycling test with three intermittent 250-m and 1-km sprints, and a 1 repetition maximum (1RM) squat test for the assessment of lower-limb strength. The weight lifters became stronger and improved their one- repetition maximum squat, but they failed to improve any aspect of cycling. Surprisingly, their final sprint in their 1- km time trials were significantly slower than their previous times. Cycling is a power sport. Those with the strongest legs are the fastest sprinters. Yet lifting weights made them slower sprinters. Lifting weights with their legs left them too sore to train most intensely on their more intense cycling days, and the faster you ride on your intense days in training, the faster you usually ride in races. Further studies in the future may change the way we think now, but most research show that resistance leg training with weights does not help experienced and well trained long distance cyclists to race faster. On the other hand, strength training may help some runners run faster. Research shows that strengthening the leg muscles of runners allows them to run faster because they stay closer to the ground and do not waste energy by bobbing up and down as much with each stride. (References at http://www.drmirkin.com/fitness/weight_training_cyclists.html ) Riding a bicycle does little to strengthen the upper body. All riders can benefit from a weight training program to improve upper body strength and give added protection against bone fractures.

http://www.drmirkin.com/fitness/weight_training_cyclists.html

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Atrial Fibrillation in Older Endurance Athletes

March 6, 2010

Runner This is a great article by Dr. Mirkin. I thought I'd share it, with his permission, to my very active clients, friends and family. A must read for EVERY athlete. Please read and share. From: Dr. Mirkin's E-zine Dr. Gabe Mirkin's Fitness and Health E-Zine March 7, 2010 Atrial Fibrillation in Older Athletes A study from Norway shows that 13 of 78 (16 percent) older competitive cross country skiers have atrial fibrillation, a condition in which the upper chambers of the heart flutter and collect blood (European Journal of Cardiovascular Prevention & Rehabilitation, February 2010). Blood that is not moving collects in the upper chambers of the heart where it can form clots that travel to the brain to block the flow of blood to cause a stroke. Almost all people who suffer from atrial fibrillation at any age are treated with drugs to prevent clotting, since they are at increased risk for strokes and heart attacks. However, the older endurance athletes are different from other people with atrial fibrillation. * The incidence of atrial fibrillation in these great older endurance athletes is the same as for non-athletic Norwegian men over 75. However, the skiers developed their atrial fibrillation at the average age of 58, which is much younger than its occurrence in the general population. * People who suffer from atrial fibrillation usually have a history of something damaging their hearts, such as high blood pressure, high cholesterol, heart disease, heavy drinking or chronic inflammation, but ten of the 13 skiers with atrial fibrillation had none of these risk factors. The older endurance athletes have the highest rate of fibrillation without any known cause in the entire world's literature. * The vast majority of endurance athletes live significantly longer than average citizens. Nobody has adequate data to show why athletes are at increased risk for atrial fibrillation or whether they are at increased risk for forming clots. My explanation is that life-long endurance athletes have large healthy hearts that contain much more heart muscle than nerves. This can interfere with the normal sequence of an electrical impulse starting each heart beat from a spot in the upper heart that causes the upper heart to contract. This electrical messages then travels along nerves down to the lower heart to cause it to beat. The large athletic healthy heart has such large muscles that they outgrow the nerves that carry each heart beat so that not all upper heart electrical impulses pass to the lower heart. Future studies will show whether this is harmful or a harmless condition in athletes. Since doctors have no data to show that older endurance athletes with atrial fibrillation are not at increased risk for strokes, they usually put them on drugs to prevent clotting. The symptoms of atrial fibrillation include: *a sensation of a rapid or irregular heartbeat, *a fluttering feeling in the chest, *sudden anxiety that the heart is beating irregularly, *sudden dizziness or faintness, *sudden shortness of breath, *sudden chest pain, *sudden loss of strength going up stairs or getting up from a chair, *sudden fatigue anytime.
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