In Part 1 of this series, we discussed swim technique adjustments for injury prevention (read it here). This week, we’ll talk about changes in bike (revolutions per minute - rpm) and run (steps per minutes - spm) cadence to reduce the load and possibly avoid overload injuries in female triathletes 40 and older.
Technique Adaptations for the Bike
Humans prefer to ride at optimal cadence, where the oxygen uptake is minimal (between 55-65 rpm).
It was previously mentioned that there might be a discrepancy between the desire to use the least energy possible and the consequent impact on the involved muscles and joints.
When reviewing common cycling injuries, riding at an excessively high pedal resistance was found as a major cause of overuse problems. Less overuse injuries were reported when using lower gear ratios at a higher cadence. These findings influence current recommendations to avoid patella tendinitis while cycling, for example: Lowering the gears, which will increase the cadence and decrease the stress in the knee area.
By increasing the pedal rate, the forces applied to the cranks are decreased, which results in the reduction of forces on the joints and minimal neuromuscular fatigue.
Adjustment to the age-related changes of reduced muscle mass and decreased ability of the connective tissue to handle impact in female master athletes, results in the reduction of stress on the musculoskeletal system.
Ideally the female master triathlete has a bike gear ratio, which allows her to ride with a cadence of at least 85-90 rpm no matter if on the flat, against slight head wind or conquering easy climbs (<5% incline).
Bike Workout Examples
These workouts will help you get used to riding at a higher rpm
- High Cadence Spins: 30 min @ Zone 1-2 in a light gear. Every 3 min, spin up to @ 105 rpm and hold for 15s. Avoid bouncing on seat.
- Spin ups: 6x 5 min. In a light gear increase cadence until starting to bounce in saddle. Back off rpm slightly and hold for 2 min. Continue with easy spin until re-start of interval every 5 min.
- RPM Ramps: 3x 10 min without change of gears. 10 min as (1 min @ 50 rpm/ 1 min @ 60 rpm/ 1 min @ 70 rpm/ … / 1 min @ 110 rpm/ 3 min easy spin). Practice first in very light gear, avoid bounce in saddle.
Technique Adaptations for the Run
Humans choose a combination of step length and step rate that minimizes VO2 in gait. This low energy cost walk/run stride rate is unfortunately not necessarily the lowest impact on the musculoskeletal system.
Recent research has suggested that runners who exhibit relatively large impact forces while running are at an increased risk of developing an overuse injury of the lower extremity.
When looking at biomechanical variables associated with injuries in distance runners, increased age was significantly associated with reduced peak knee flexion and increased contact time.
It can be concluded that female master athletes run with lower stride rates and increased stride length to their detriment.
As a negative effect, there is an increasing need for the body to absorb impact as the stride length increases. The energy absorbed during the impact portion of the running cycle increases simultaneously.
Inversely, decreasing stride length has been found to be a potential mechanism of strain reduction during running.
It was found by different research teams that a 10 percent reduction in stride length lowered nearly all lower extremity contact forces. It was concluded that this technique adaptation has significant potential: Reducing stride length decreased the probability of stress fracture by 3 to 6 percent.
Luckily, females with a naturally smaller build tend to find it easier to run with shorter steps compared to taller athletes who are more likely to overstride. Overstriding is running with a reduced cadence but longer stride length, which increases susceptibility to injury.
To avoid over striding, strive to take the stride rate to the next level. Advance in small increments to allow your anatomical structure time to adjust to the new technique. Ideally, reduce spm by 5 steps per minute, then maintain for a few weeks until all runs are consistently at the new rate. For constant feedback during runs, it is recommended to use a metronome or an app on your phone.
A general goal for female runners over 40 years of age is greater than 160 spm regardless of the pace. The long-term goal is to keep the rate above 170 spm during all runs to prevent possible impact injuries.
Run Workout Examples
These workouts will help you get used to running at a higher spm
- SPM Intervals: Run at current cadence for 15 min @ Zone 1-2. Every 3 min, increase stride rate for 20s. Hit lap button at start/ end of interval to track differences.
- 10x 1 min @ +5 spm: Start each minute for 10s with metronome, then continue for 50s without feedback. Use current cadence +5 spm (eg instead 155, set metronome to 160 spm)
- 30 min with 30s Feedback intervals: Try to run @ +5 spm of current cadence. Every 5 min, turn metronome on for 30s and compare if on target.
Adjustments to bike and run cadence are challenging at first, but they’ll will result in long term benefits.
Lisi Bratcher is the owner of fit.active LLC, a multisport coaching company focusing on Swimming and Sports Nutrition, based in Huntsville, Alabama. Born and raised in Europe, Lisi received a Ph.D. in Exercise Science and from the University of Vienna in Austria. Today you'll find her teaching Exercise Physiology and Health &Physical Education classes at the University of Alabama in Huntsville, as well as coaching intermediate to advanced triathletes. She is a certified ACSM Exercise Physiologist, a certified Track & Field coach, and a USA Triathlon Level I Certified Coach. Find her on Facebook at triHSV or contact her at email@example.com.
The views expressed in this article are the opinion of the author and not necessarily the practices of USA Triathlon. Before starting any new diet or exercise program, you should check with your physician and/or coach.