We tend to forget what vital signs mean. In Medicine, vital signs are the most
important aspect of the patient to consider.
I follow a 95-year-old patient daily and the vital signs are our
guidelines for treatment. Historically
we have four vital signs: blood pressure, temperature, heart rate and
respiratory rate. The vital signs should
change as much as they could change in teenager for a 95-year old lady. When she runs out of oxygen in the middle of
the night because she removes it while sleeping, her pulse can be 10 beats
higher in the morning as if she had a hard work out during the night. Her saturation can drop to low 80’s if she
does not have oxygen at night. I do not
need to know what happened during the night when checking the heart rate in the
morning; during the day her saturation stays above 92 without oxygen.
Temperature should not change or being above 37
degrees Celsius. If it is higher than
that we should stop practice for the day at least and a differential diagnosis
for fever should take place. DO NOT LET
THE DIAGNOSIS OF HAVING AN INFECTION FOOL YOU.
Above 37 degrees Celsius of core temperature can help you to understand
athlete´s life; is the athlete resting well? Is the athlete eating well? Check
the Complete Blood Count and find out about the erythrocyte production. Even if the athlete does not have anemia,
nutrition could be a problem for repetitive infections (we all have bugs but
other factors play a role in athlete’s illness). Even if athletes eat well, resting is another
variable; and by the same token, lesions in athletes (ask the footballers). We found out that our triathletes were out in
the middle of night after we checked lactate levels at rest in the morning and
they were 2 or above.
High blood pressure should not be present in athletes
unless something very important is happening somatically. Is the athlete withdrawing from drugs? Is the
athletes falling into kidney failure (you should have many other signs by
then)? No athlete should faint unless
something is really bad (Laurent Vidal fainted years before he died).
Respiratory rate and heart rate are intertwined. The second to second regulation is done by
the amount of CO2 in arterial blood.
They both go up when CO2 increases but there are adaptations to this
phenomenon of CO2 increment. The
respiratory rate adapts first, so the heart rate stayed up and helps to monitor
fitness or CO2 retention without the need of getting Arterial Blood Gasses in
somebody who is monitored several times during the day. This is our observation in a 95-year–old lady
who has been monitored for more than a year.
Weight is not a vital sign but helps to monitor
patients. Weight increment of 1.5
kilograms is the norm comparing the morning weight and evening weight in the same
athlete.
How can we apply this to triathlon? Let’s take the
heart rate and weight. We have had the cardiac
monitor for several decades already. It
is part of an educated triathlete, but how much we want to ignore about weight?
There is a study (many studies have been published)
which gives information about weight in horses the way we can understand
running in humans:
Table 2 shows the velocity versus oxygen
consumption for a TB horse. Column one is the horse speed (feet per
second, ft/sec) on the treadmill, column two through five are the oxygen
consumption values (ml/kg/min) on the treadmill, column three for running on
sand (simulate the race track), column four is for a jockey weight of 130
pounds and the last column for a jockey of 110 pounds. The table
shows that at a constant speed the oxygen required increases as the load
condition increases running in sand or carrying weight.
Table 2:
Velocity Oxygen Running Jockey Jockey
Consumption in
Sand Weight Weight
|
Vel,
ft/sec
|
O2,
ml/kg/min
|
1.2
|
130
|
110
|
|
5
|
15.5
|
18.6
|
20.84
|
20.49
|
|
10
|
26
|
31.2
|
34.96
|
34.38
|
|
15
|
36.5
|
43.8
|
49.07
|
48.26
|
|
20
|
47
|
56.4
|
63.19
|
62.14
|
|
25
|
57.5
|
69
|
77.31
|
76.03
|
|
30
|
68
|
81.6
|
91.42
|
89.91
|
|
35
|
78.5
|
94.2
|
105.54
|
103.79
|
|
40
|
89
|
106.8
|
119.66
|
117.68
|
|
45
|
99.5
|
119.4
|
133.77
|
131.56
|
|
50
|
110
|
132
|
147.89
|
145.44
|
|
55
|
120.5
|
144.6
|
162.01
|
159.33
|
|
60
|
131
|
157.2
|
176.12
|
173.21
|
|
65
|
141.5
|
169.8
|
190.24
|
187.09
|
|
70
|
152
|
182.4
|
204.36
|
200.98
|
|
75
|
162.5
|
195
|
218.47
|
214.86
|
|
80
|
173
|
207.6
|
232.59
|
228.74
|
|
85
|
183.5
|
220.2
|
246.71
|
242.63
|
The same thing is happening to humans running but the
effort can be greater when relating them to the center of gravity and weight.
The effect of weight at other locations
other than the center of gravity can have a significant impact on oxygen
consumption levels. Myers
(1985) found that the cost of adding a given mass to the limbs is significantly
greater than adding it to the center of mass and that this effect becomes more pronounced
as the limb loads are moved distally (towards the foot). Miller (1987) showed a 0.8% increase
in oxygen consumption for ankle weights of 100 grams on human runners. A 600-gram weight at the center of
gravity would result in the same increase of oxygen consumption. Relative to horse racing, any increase
in extra weight carried along the leg and at the hoof could impact on a horse’s
performance. For example on
a muddy or sloppy day a large horse (large hoof) could end up carrying extra
dirt in its hoof relative to a smaller horse (smaller hoof). Also the come from behind type of
runner could have additional weight along the legs from mud being thrown back
from horse’s in front. This
extra weight could be enough to cost a win.
We are not kicking a dead horse! Flying while running has implications for
performance if we consider weight into the equation. If we have a cadence of 200 rpm running a
mile in 4 minutes and we cannot compete in triathlon running the last
10k, it is because we cannot fly in triathlon after the effort on the bike or
due to the way we pedal during the race.
In addition to what we know scientifically we have many examples of low
cadence running and inability to run in an Olympic distance triathlon. I have
seen Lukas Verzbicas running the last 10k in Puerto Progreso this last weekend
and he was running above 33 minutes the 10k.
I have seen videos of Alan Webb running after swimming and biking and he
was not able to “fly.” They keep the same cadence without flying. What have we learned from horses? Keeping the weight (if extra-weight) at the
center of gravity does not affect performance so much. Increasing cadence is another one, it keeps
the center of gravity in front of us most of the time; horses increase cadence
to go faster because they cannot increase flying time as humans do. Flying after the bike is very difficult to do
and sometimes impossible because the way we develop our muscle doing our
bicycling training.
How we can keep weight at the center of
gravity? We need technique for running.
Yes, there is a technique for running and we have pointed out in this
blog.
28 juin 2013
