CYCLING PERFORMANCE TIPS
Last updated: 1/31/2013
Skeletal muscles makes up over 1/2 of the body weight in a lean individual. All muscles
(quadriceps, biceps, etc.) are composed of thousands of muscle cells. And these individual
muscle cells contain two proteins - actin and myosin - which chemically interact and
shorten the cell (and along with it the muscle itself) when the muscle cells are stimulated
by the release of calcium initiated by a nerve impulse. The interaction of the
actin-myosin complex, which results in the shortening or contraction of the muscle
cell, requires the energy in the form of ATP.
Interestingly, a recent study has demonstrated a direct positive effect of caffeine
on the muscle fiber itself resulting in an increase in the mobilization of
calcium from the sarcoplasmic reticulum of the muscle cell. The result was
a reported 7% increase in power output over a 6 second cycle exercise task.
TWO TYPES OF MUSCLE FIBERS
The muscle cells contain two distinct types of muscle cells or fibers.
Type I (slow twitch, SO fibers) - These muscle cells shorten at a relatively slow speed
and generate energy from both fats and carbohydrates via aerobic metabolism . They are
the major muscle fiber in use at 70-80% VO2max. Type I cell characteristics include:
Type II (fast twitch, FG fibers) - These muscle cells are less efficient than the slow
twitch cells and are almost entirely dependent on glycogen as fuel. They are called
into action for sprints when the athlete approaches 100% of their maximum performance
(and are working in the anaerobic range above 100% VO2max). Type II cell characteristics
- high concentration of mitochondria for aerobic metabolism
- increased intracellular myoglobin (which gives the muscle its characteristic red color)
to store and transport O2
- low concentration of glycolytic enzymes used for anaerobic metabolism
- relatively fatigue resistant
The relative proportion of type I and type II fibers within a
muscle varies from person to person and is determined by genetics (ie inheritance from
your parents). However, with limits, this ratio can be modified with exercise and training.
Successful endurance athletes have a preponderance of slow twitch muscle fibers (up to 90%
of the fibers in the calf in cross country skiers) while sprinters have more fast twitch
fibers. Short term studies in bicyclists (5 months) failed to show a change in the ratio
of cell types (percentage of slow vs fast twitch fibers) in leg muscles, but a longer
multi-year study has suggested that this ratio can change with time, continuing to
change for at least 5 years with regular training.
- low concentration of mitochondria
- high concentration of ATP and glycolytic (ATPase) enzymes
- a rate of shortening 3 to 5 times that of a type I muscle cell
But even without a change in the ratio of cell types, there is no question that both
slow and fast twitch fibers can markedly improve their metabolic capacity with training.
(see also Principles of Training)
But all training may not be positive for muscle cell adaptation.
A recent article (Derman et al, Journal of Sports Medicine, 15:341-351, 1997) described muscle
cell biopsy changes in athletes that:
Muscle biopsies from the vastus lateralis demonstrated cell structure abnormalities. They
speculated that repeated bouts of high volume training over years (with repeated micro trauma)
might lead to chronic muscle structure changes and symptoms. At this time there is not
enough evidence to call this, but it may represent a unique subset of elite athletes
that present with training problems.
- had a history of high volume exercise training for years (5 of 9 had performed at
the national or international level)
- presented with chronic fatigue
- had a syndrome of excessive late onset muscle soreness and stiffness
MEASUREMENT OF ENERGY OUTPUT (POWER)
Energy output (or work) is expressed as
power (the amount of work done during a specified unit
of time). Power output can be measured as steady state power output (maintaining a steady
speed for minutes to hours) or maximal power output - which require maximal activation of the
ATP-CP energy system. The latter reflects the maximal muscle
power of the athlete and is limited by the amount of ATP and CP available in the cell -
about 6 seconds.
Curt Austin has put together a nice calculator to estimate power output (in Watts - you enter
your own parameters) on his
website. Malcolm Firth also published some comparative numbers in an online coaching
forum. (As the amount of ATP-CP available to the muscle cell is limited, Malcolm's maximum
power output over several minutes would be lower than that achievable in a brief sprint
lasting 5 to 5 seconds):
"In February 1998 I did a small research project in which a group of 24
cyclists were asked to do two tests on a CompuTrainer (an electromagnetically
braked turbo trainer made by RacerMate of Seattle, USA). The first of these
was a step increased load test to voluntary exhaustion in which the load
began at 100 watts and was increased at approx 20 watts per minute. After a
break of at least three hours the cyclists then rode a simulated ten miles
time trial on the CompuTrainer with the instruction to complete the distance
as quickly as possible. Some of the data is summarized below:
The average 10 mile heart rate worked out at 94.5% of the mean max heart
rate.(st dev 2.81%, range 88.41%-97.41%). If you go to my web site at
http://www.msfirth.freeserve.co.uk you will find an article giving details on how to use
the average ten miles heart rate to estimate heart rates for other training and racing
- Average Age: 33.17yr (standard deviation 12.97, range 16yr-61yr)
- Average Max Power for 1 min: 367.46 watts (st dev 62.74w, range 263w-487w)
- Average Max Heart Rate: 187.29bpm (st dev 12.16bpm, range 163bpm-211bpm)
- Average 10 mile Time: 25min 52sec (st dev 1min 50sec, range
29min 09sec - 23min 02sec)
- Average 10 mile Power Output: 286.46 watts (st dev 49.88w, range 215w - 375w)
- Average 10 mile Heart Rate: 177.08bpm (st dev 11.78bpm, range 145bpm-199bpm)
Q.I was hoping you could shed some light on how I might be able to shed some
upper body muscle mass to lighten up a bit. I have 7% body fat and have not been to
the gym in a year, although most of my life has been dedicated to weights until now.
I don't want to lose any leg strength in the process.
A. Except for inactivity (accelerated by overall weight loss) , I am unaware of
any way to decrease muscle mass. Thus I think you are looking at a long term program of
increasing or maintaining lower body stress on the muscles (biking, weight lifting) to
maintain or increase mass there while discontinuing all upper body weight work.
Questions on content or
suggestions to improve this page are
Cycling Performance Tips
Table of Contents