Chapter 10 Conditioning and Retraining the Canine Athlete 259period diminished only minimally during the
first 12 weeks of detraining, but declined more
between 12 and 31 weeks of detraining (Lemmer
et al., 2000). Another study performed in young
soccer players found that long‐term detraining
(>4 weeks) decreased oxygen uptake, Vo2max, and
aerobic and anaerobic running speeds (Melchiorri
et al., 2014).
Similarly, a study performed in elite taek
wondo athletes found 8‐week detraining sup
pressed physiological stress but rapidly
resulted in declines in athletic performance and
health metabolic profiles, including reduced
aerobic capacity, increased body fat, muscle
loss, insulin resistance development, and ele
vated systemic inflammatory status. The
inflammation state was positively associated
with insulin resistance development, fat mass,
central fat accumulation, and the decline in
Vo2max (Liao et al., 2016).
However, another study performed in elite
women pole‐vaulters found that after 28 days
of inactivity, the rate of force development
(RFD) and the ability to accelerate over very
short distances (5 m) while sprinting improved
after training cessation. Acceleration over
longer distances (5–45 m) was impaired, while
unloaded and loaded vertical jump tests suf
fered trivial to small changes. Further, this
study concluded that detraining periods of
approximately 1 month or even longer may be
implemented in elite pole‐vaulters without
significantly impairing performance (Loturco
et al., 2017). Together, these studies suggest
that continued exercise, even of a relatively
gentle nature, is essential to maintain levels of
fitness that will shorten the length of time for
recovery from an injury and return to competi
tion sports.
Age‐appropriate conditioning
and sports training
Young, growing dogs undergo significant physi
cal changes, especially during the first 12–18
months of life before the physes have closed.
This means they have different capabilities for,
and adaptations to, exercise. For this reason,
training programs for young canine athletes
should not be just scaled‐down versions of adult
training programs. There are marked differences
in coordination, strength, and stamina between
puppies and adults. Puppies have lower anaero
bic capabilities, are less metabolically efficient,
and have less efficient thermoregulatory mecha
nisms (Bright, 2001).
For long‐term health in canine athletes and
working dogs, it is important to avoid intense
and particularly concussive training until the
physes are closed. The physes of different bones
close at different ages (Table 10.3). The larger
the breed, the later the physes close. In addi
tion, it is well established that the physes of
dogs that are spayed or neutered prior to
puberty experience delayed closure (Salmeri
et al., 1991). The best way to know whether the
physes of a gonadectomized dog are closed is
to perform a lateral radiograph of the stifle as
the tibial tuberosity is the last physis in the
body to close.
The difference in texture between the calci
fied bone and the uncalcified physes makes the
physes susceptible to injury. The physis is the
weakest area of the growing skeleton, weaker
than the nearby ligaments and tendons that
connect bones to other bones and muscles
(Shire & Shultz, 2001). In a growing dog, a seri
ous injury to a joint is more likely to damage a
growth plate than the ligaments that stabilize
the joint. An injury that would cause a sprain in
an adult dog can injure the physis in a youngTable 10.3 Ages at which the physes closePhysisClosure age
(months)Thoracic limb
Tuber scapulae 4–7
Proximal humeral epiphysis 9–15.5
Humerus: lateral and medial condyles 6.25
Proximal radial epiphysis 4.5–11
Distal radial epiphysis 4.5–17
Pelvic limb
Femoral head 4.3–18
Femoral distal epiphysis 4.5
Tibial condyles 4.75–13.75
Tibial tuberosity 4.75–14.5
Tibial distal epiphysis 4.5–16.5Source: Adapted from Newton and Nunamaker,1985.