Cross-training may be highly beneficial to overall fitness
in the general population. Cross training tends to have a greater
effect on deconditioned individuals as compared to highly trained
athletes. However cross-training may be appropriately implemented
to supplement training during periods of injury rehabilitation,
overtraining, or psychological fatigue. Also see Specificity
of Aerobic Training.
Tanaka H (1994). Effects of cross-training. Transfer of
training effects on VO2max between cycling, running and swimming.
Sports Med. 18(5):330-9.
Performance Effects of Environment
The optimum temperature for long distance running performance
seems to be around 50-55°F (10-13°C). Performance degrades
as much as 2% for every 5°F (2.75°C) above or below this
range. High humidity in high temperatures can increase the effective
ambient temperature by up to 10°F (5.5°C) by inhibiting
evaporation. Direct sunlight can increase temperature by up to
8-9°F (5°C). Special caution should be advised when the
temperature exceeds 80°F (27°C) or relative humidity
surpasses 50-60%. Also see Wind
Chill Chart and Heat
Humidity Index Chart.
A steady state of oxygen uptake can be maintained during prolonged
low-intensity exercise. Exercise at a relatively high work rate
or in a hot and humid environment results in an upward drift
in oxygen consumption over time so a steady state is not obtained
under these circumstances. During incremental (graded) exercise,
oxygen uptake increases linearly until VO2 max is reached.
Fat Metabolism & Aerobic Intensity
The total rate of fat oxidation during exercise is greatest
at higher intensities that are below lactate threshold. For example,
during exercise at 20% of VO2 max, approximately 60% of the energy
would come from fat. By comparison, exercise at 50% of VO2 max,
only about 40% of the energy would come from fat. Nonetheless,
the absolute amount of fat metabolism is 33% higher during exercise
at 50% VO2 max since the total energy expenditure is 250% greater
than exercising at only 20% of VO2 max. The greatest absolute
fat metabolism during exercise occurs at 50% of VO2 max in untrained
subjects (body weight: 89 kg; VO2 max: 4.0 L/min; lactate threshold:
60% of VO2 max).
Lactate threshold (controversy AKA anaerobic threshold) is
the point at which blood lactic acid rises systematically during
graded exercise. Lactate threshold occurs in untrained subjects
around 50-60% of VO2 Max and in trained subjects around 65-80%
of VO2 Max. Lactate threshold can be used as a marker of training
intensity. It can also be used in combination with other physiological
measurements, such as VO2 max, as a predictor of long-distance
running performance (Farrel P, et al. 1979; Marti B, Abelin T,
Howald H, 1887).
Progression and Recovery
After a hard workout, take a day off or have an easy workout.
Increase your weekly distance no more than 10 percent. After
a few weeks of distance increases, drop distance by 50 percent
for one week. Occasionally, reduce your weekly distance by 10-15
percent while increasing your pace by 6 to 12 seconds per kilometer
(10 to 20 seconds per mile).
Precor Elliptical (EFX) Distance Conversions
Trainer and Elliptical
You burn 7% fewer calories for every 10 pounds (4.5 kg) of
weight you lean on the handrail of a stair climbing machine.
(typical 143 lb person x 7% = 10 lbs)
Outdoor vs Treadmill Running
The Aerobic demand for outdoor running at 5 m/s is 5% to 7%
higher than that for treadmill running.
Jones AM, Doust JH. A (1996). 1% treadmill grade most accurately
reflects the energetic cost of outdoor running. J Sports Sci.
Concept II Rower (2500 Meter Records):
- Men: 7:10.7
- Women: 8:12.5
Group Exercise Music - Beats per Minute (BPM)
Floor work / Muscular conditioning
Your feet are not identical so fit the larger one when buying
shoes. The best time of day to shop for a shoe is at the end
of the day, when your foot is the largest. A long jog in warm
weather can expand a runner's feet as much as half a size. Test
shoes before you buy them. Good shoes should feel comfortable
when you first try them on, not after they have been broken in.
Buy new running shoes every 240 to 450 miles (400 to 725 km).
Buy new walking shoes every 400 hours of use (e.g.: after 40
week of 10 hours of walking per week). Many models of running
shoes are now especially designed for those who pronate as well
as those with a standard gait.
- Left: Standard
- Middle: Pronate
- Right: Supinate
Average Marathon Times in US (2005)
- Men: 4 hours 32 minutes 8 seconds
- Women: 5 hours 6 minutes 8 seconds
Marathon World Records
- Men: 2:3:59, Haile Gebrselassie (Ethiopia), Berlin Marathon,
Sept 28, 2008
- average pace: <2:57 per kilometer (4:44 per mile)
- average speed >20.4 km/h (12.6 min/hr)
- Women: 2:15:25, Paula Radcliffe (Great Britain), London Marathon,
April 13, 2003
Walking the USA
In 1909 Edward Payson Weston walked 3,795 miles from New York
to San Francisco in 104 days and 7 hours. Along the way he endured
many obstacles such as heavy blizzards. At the time, he was celebrating
his 70th birthday.
The following year Weston walked back to New York from Los
Angeles. He completed the 3,600 mile trek in 76 days and 23 hours.
Running and Pain After 50
Runners 50 years of age or older suffer 25 percent less musculoskeletal
pain than their peers who do not run.
B Fries, JF Fries, DP Lubeck (2005). Aerobic exercise and
its impact on musculoskeletal pain in older adults. Arthritis
Research and Therapy, 6(7): 1263-70.
Decline in Aerobic Endurance
Entering the second half of life, the average adult loses
1.5 percent of aerobic capacity per year (Cooper 2007).
- The aorta, one of the largest arteries in the body, is the
diameter of a garden hose.
- In contrast, ten capillaries are equal to the thickness of
a single human hair.
- The human body contains about 6 quarts of blood which circulate
through the body three times every minute.
- Each day, the blood travels about a total of 12,000 miles
(19,300 km) per day (4 times across the US from coast to coast).
- In a lifetime the human heart will pump about 1 million barrels
of blood - enough to fill over 3 super-tankers!
Diagram of the Organs of the Circulation
- L: pulmonary circulation
- M: circulation through the organs suspended by the mesentery
- P: circulation through the liver
- The circulation through other organs, such as brain, muscles,
skin, and kidneys, is indicated.
- Lymphatics are represented by dotted lines.
Heart Volumes (ml)
Heart Pump / Machine Pump
A Horse's Dynamic Red Blood
In the horse, circulating hemoglobin concentration doubles
from rest to maximum exercise. This great augmentation of oxygen
delivery to the working muscles presumably accounts in part for
that species' remarkably high VO2 max (approximately 160 ml/kg/min).
This is 3 to 4 times higher than in a fit healthy human. In humans,
there is virtually no contribution to the increase in VO2 by
hemoglobin concentration changes from rest to exercise.
Wagner, PD, (1991) Central and peripheral aspects of oxygen
transport and adaptations with exercise, Sports Medicine, 11