Need some assistance with two question SPHE314 1003

Detraining causes losses in muscular strenght and power.

However muscles require only minimal stimulation to retain these qualities during periods of reduced activity

(a training session once every 10 to 14 may be sufficent)

Muscular endurance decreases after only 2 weeks of inactivity.Possible explanations for this are:

• decreased oxidative enzyme activity

• decreased muscle glycogen storage

• disturbance of the acid-base balance

• decreased blood supply to the muscles

Detraining losses in  speed and agility are small. Flexibility is lost rather quikly, so stretching exercises should be incorporated also into off-season training programs.

Although flexibility can be reestabilished in little time, the athletes should maintain the desired flexibility level year-round.

Reduced flexibility has been  proposed to increase athletes’ susceptibility to serious injury


similarities:

Both results in:

decreased oxidative enzyme activity
decreased muscle glycogen storage
disturbance of the acid-base balance
decreased blood supply to the muscles
Some evidence suggests that chaanges red blood cells.
Single lower limb IM allows for the study of the targeted muscles in a given limb.
in both cases person will undergo an extensive training program to re-strengthen their muscles.


ADAPTATIONS TO SPACEFLIGHT

While the human body cannot adapt to such conditions as anoxia (lack of oxygen), hypobaria (lack of pressure) and radiation, it can and does adapt to weightlessness. These alterations in body equilibrium are here divided into short-term (hour to days) and long-term (weeks to months) changes.

In the first few minutes of weightlessness, the body's fluids shift dramatically. Since gravity is no longer keeping fluid (in the forms of blood and extracellular fluid) pooled in the legs, fluid redistributes up into the chest and head. This causes the characteristic 'puffy face' and 'birds legs' appearance of astronauts, as well as nasal congestion (probably contributing to loss of sense of smell as well).

The body's sense of balance is partially due to the inner ear (semicircular canals) and feeling of weight in certain joints (proprioception). With the loss of gravity, both sensations are disabled: fluid in the semicircular canals no longer convey feelings of rotation or 'up and down', and there is conflict between what we see and what we 'sense'; for instance, your eyes can tell you you're upside-down, but your 'balance' says you are tumbling. This conflict between what you see and what you feel causes Space Adaptation Sickness, or 'space-sickness': early onset of vomiting, headache, and a sick feeling that subside suddenly after 2 or 3 days in space. As the first day of spaceflight wears on, the kidneys try to compensate for what they perceive as excess fluid by excreting more of it, resulting in abnormally low fluid volume. Mineral concentrations increase, resulting in increased risk of kidney stones. The body then decides it has too many red and white blood cells for its volume, and proceeds to eliminate some of these, resulting in relative anemia.

In the next few days, the body adapts further to its new conditions. Without gravity to compensate for, muscles do not need to work so hard to move things, and muscular atrophy occurs. The heart is also a muscle; since blood no longer has weight, the heart 'eases up', becoming weaker. Levels of Thyroid hormone increase, which speeds up metabolism and contributes to body mass loss. Immune system function (both cell- and antibody-mediated) decreases, and capacity for exercise decreases.

As days turn into weeks, both muscle and bone readjust. Stress in our bones keeps them strong; without gravity, stress is lost and bone is reabsorbed at the rate of 1-2% per month (depending on the individual and site of measurement). Muscles atrophy and lose protein, further contributing to loss of body mass. Many countermeasures have been tried to stop or reverse this readjustment, but even the most successful only partially slow its advance (more on countermeasures in a later article).

As the initial excitement of launch and the new environment wear off, psychological adaptations can cause problems. Soviet investigators described three phases of psychological adaptation to spaceflight, based on long-term flights of Salyuts and Mir. The 'acute' (first month) phase involves adjustment to the new and busy environment. An intermediate phase is marked by increasing fatigue and loss of motivation, irritability and emotional lability ('asthenia'). If countermeasures are not instituted, a final 'long-duration' stage of hypoactivity, feelings of isolation and worsened asthenia proceeds. Sleep is prolonged and disturbed, depression and hostility worse, and productivity plummets. Both cosmonauts and astronauts have become hostile, refused to work and become more withdrawn during long-duration missions. Not all researchers share Dr. Zubrin's optimism concerning psychological problems in long-duration spaceflight.

On return to a gravity field, the body must readapt to the unaccustomed conditions. To make matters worse, during reentry Shuttle crews encounter about 1.5 G's, half again Earth's normal gravity. On returning to Earth, 10% of astronauts (and most cosmonauts, who've been up longer) cannot stand upright. Most feel unsteady and weak; many vomit. Almost all have difficulty accurately pointing to and manipulating switches and buttons in front of them: as gravity increases, the arms feel unaccustomedly heavy and awkward, and pilots 'overshoot' the controls.