Chapters 5/6

Selective Recruitment Principle -- what is it? -- which athletes is it important for?

In Highly Trained athletes, the nervous system will adapt and allow the athletes to recruit out of order for greater force production. -- an athlete is able to inhibit the lower-threshold motor units and in their place activate higher-threshold motor units -- critical for athletes dependent on generating power quickly for explosive high velocity movements (ie vertical jump) -- using specific training methods may enhance selective recruitment, which in turn may improve sport performance Note: With heavy resistance training, all muscle fibers get larger (i.e., hypertrophy) because motor units are recruited in a sequential order by their size to produce high levels of force. In advanced lifters, the central nervous system may adapt by allowing well-trained athletes to recruit some motor units in a nonconsecutive order, by recruiting larger ones first to promote greater production of power or speed in a movement.

What Are the Markers of Anaerobic Overtraining?

Psychological effects: decreased desire to train, decreased joy from training Acute epinephrine and norepinephrine increases beyond normal exercise-induced levels (sympathetic overtraining syndrome) Performance decrements, although these occur too late to be a good predictor

Bone Remodeling Process: -- where does new bone formation occur? -- What is Minimal Essential Strain? -- What is the force needed for MES?

-- *New bone formation occurs predominantly on the outer surface of the bone (periosteum), increasing diameter and strength* -- In response to mechanical loading, osteoblasts migrate to the bone surface and begin bone modeling -- *Minimal essential strain (MES)* refers to the threshold stimulus that initiates new bone formation. Consistently exceeding these thresholds signals osteoblasts to migrate to the region experiencing the stress and to form bone. >>> (MES is thought to be approximately 1/10 of the force required to fracture bone. Increasing the diameter of bone allows the force to be distributed over a larger surface area, thereby decreasing the amount of mechanical stress. Following bone growth, a force that previously exceeded the MES will now be below the MES threshold.)

Detraining and VO2 max -- how long does it take for VO2Max to decline? -- what is associated (hr, sv, etc) with decreased in VO2Max?

-- *Noticeable decline in .VO2 with ceasing aerobic exercise, begins around 12 days after stopping* --- Detraining even worse effect on .VO2 than aging, worse off after 3 weeks of bedrest than aging 30 years --- In highly trained athletes, maximal oxygen uptake is reduced 4% to 14% with short-term (and 6% to 20% with long-term detraining *Reduction in VO2max is primarily a result of decreased blood volume, decreased stroke volume, decreased maximal cardiac output, and increased submaximal heart rate*

Why do tendons and cartilage heal slowly, if at all, following injury? Which one has poor blood supply versus no blood supply?

-- A feature unique to cartilage is that it lacks its own blood supply and must depend on diffusion of oxygen and nutrients from synovial fluid (which is why cartilage does not easily repair itself following injury) -- Compared with that of muscle tissue, tendon metabolism is much slower due to poorer vascularity and circulation. In fact, the increase in blood flow to skeletal muscle via exercise is not paralleled by the same flow perfusion in tendons

Compatibility of Aerobic and Anaerobic Modes of Training

-- Combining resistance and aerobic endurance training may interfere with strength and power gains, >>>>>HOWEVER>>> -- the majority of research indicates that heavy resistance training has very limited, if any, negative effects on aerobic power but instead can serve to actually enhance performance in endurance sports Note: increasing the recovery period between workouts may decrease the incompatibility (incompatibility may be due to overtraining without adequate days off for recovery)

How does a muscle hypertrophy?

-- The process of hypertrophy involves both an increase in the synthesis of the contractile proteins actin and myosin within the myofibril and an increase in the number of myofibrils within the muscle fiber itself. The new myofilaments are added to the external layers of the myofibril, resulting in an increase in its diameter.

3 Adaptations of Motor Units to Anaerobic Training:

-- improved *activation* of available motor units -- increased *firing rate of motor unit for improved force generation via summation* of mm contraction -- *greater synchronization of neural discharge*, which acts to coordinate the activity of multiple muscles in synergy Summation: With increased motor unit firing rates, the muscle fibers are *continually activated by subsequent action potentials before they have time to completely relax following a prior action potential*. The summation of overlapping action potentials is expressed as augmented contractile strength

Size Principle of Recruitment -- define -- training implications?

-- represents the *relationship between motor unit twitch force and recruitment threshold* -- *motor units fire in order from small to large and are derecruited in opposite order* Training Implications: -- with heavy resistance training, all fibers recruited so they all experience hypertrophy -- Once a motor unit is recruited, less activation is needed in order for it to be rerecruited (This phenomenon may have important ramifications for strength and power training, as the high-threshold motor units may be more readily reactivated subsequent to prior recruitment)

Overtraining syndrome -- cause? -- duration? -- symptoms? -- Sympathetic vs Parasympathetic OTS

-Result of constant intense training that doesn't provide adequate time for recovery -Symptoms: increased RHR, impaired physical performance, reduced enthusiasm and desire for training, increased incidence of injuries and illness, altered appetite, disturbed sleep patterns, and irritability. -- Overtraining syndrome can last as long as six months The *sympathetic overtraining syndrome* includes increased sympathetic activity at rest, whereas the *parasympathetic overtraining syndrome* involves increased parasympathetic activity at rest and with exercise. >>>> Eventually all states of overtraining culminate in the parasympathetic syndrome and the chronic suppression of most physiological systems throughout the body

List the acute effect of anaerboic exercise on: CO, stroke volume, BP, blood flow to active muscles -- which contraction increases BP more, eccentric or concentric? -- long term BP change due to anaerobic exercise? -- difference in CO and stroke volume, eccentric vs concentric

Acute anaerobic exercise results in increased cardiac output, stroke volume, heart rate, oxygen uptake, systolic blood pressure, and blood flow to active muscles. -- Rise in BP higher during the concentric phase of each repetition than during the eccentric phase -- No change to resting BP level as a result of anaerobic exercise -- Stroke Volume, Cardiac Output higher during Eccentric contraction (higher interthoracic pressure during concentric bc it is more difficult lowers venous blood return to heart) >>> Note: Chronic resistance training reduces the cardiovascular response to an acute bout of resistance exercise of a given absolute intensity or workload. Short-term studies have shown that resistance training results in adaptations that blunt the acute increases in heart rate, blood pressure, and double product caused by the resistance training workout.

Adjustments to Altitude Hypoxia -- how long until HR/CO returns to normal at altitude? -- how long until effects of attitude are lost when return to sea level?

Adjustments to Altitude Hypoxia Two adjustments that occur early in the acclimatization process are particularly important: 1. There is an increase in pulmonary ventilation (hyperventilation) at rest and during exercise. This increase in ventilation is primarily the result of increased breathing frequency. With longer stays at high elevation, however, increased tidal volume also contributes to augmented ventilation. Stabilization of ventilation is dependent on the level of altitude and the duration at altitude 2. Increase in cardiac output at rest and during submaximal exercise, due primarily to increases in heart rate. *Within 10 to 14 days at a given altitude, heart rate and cardiac output begin to return to normal values* because of the longer-term acclimatization response of increased red blood cell production >>> *Acclimatization changes revert in about one month after return to sea level.*

VO2 max equation

Cardiac Output x AV-O2 diff Units = ml O2Kg-1min-1 or Lmin-1 AV-O2 diff = the difference in the oxygen content between arterial and venous blood

Formula -- Cardiac Output -- max heart rate -- Rate Pressure Product -- Mean Arterial Pressure

Cardiac output is the amount of blood pumped by the heart in liters per minute: CO = HR x SV Max Heart rate: 220- age (+/- 10 bpm standard dev) Rate-pressure product = Heart rate x Systolic blood pressure -- *used to estimate the work rate of the heart * Mean arterial blood pressure = [(Systolic blood pressure − Diastolic blood pressure) ÷ 3] + Diastolic blood pressure ---- Mean arterial pressure is not the average of systolic and diastolic pressures, because the arterial pressure usually remains nearer the diastolic level than the systolic level during a greater portion of the cardiac cycle.It is defined as the *average blood pressure throughout the cardiac cycle*

Define: Cross-Education Bilateral Deficit

Cross-Education -- training one side will lead to improved strength on contralateral side due to improved neural firing from central neural adaptation Bilateral Deficit -- untrained people will actually have lower strength output when contracting bilateral muscles than the sum of the individual muscles contracting unilaterally

Detraining -- what causes initial strength reduction from detraining? -- effect on mm fiber distribution, CRA (acute, long term)?

Detraining is the term given to a decrement in performance and loss of the accumulated physiological adaptations following the cessation of anaerobic training -- *strength reductions appear related to neural mechanisms initially, with atrophy predominating as the detraining period extends* -- In strength-trained athletes, 14 days of inactivity has been reported to have* no effect on muscle fiber type distribution*. In comparison, *muscle fiber cross-sectional area declines rapidly* in strength and sprint athletes >>> initial changes specifically targeted *fast-twitch fibers initially, with no significant change immediately found in the slow-twitch fiber population.*>>> Longer periods of stoppage bring about declines in both fast- and slow-twitch fiber cross-sectional area and muscle mass in anaerobically trained athletes.

Gas Diffusion of PaO2 and PaCO2 Trace from inspiration to expiration: -- normal levels -- during exercise

During high-intensity aerobic exercise, the partial pressures of these gases are approximately 3 mmHg for oxygen and 90 mmHg for carbon dioxide. Consequently, these pressure gradients cause the movement of gases across cell membranes. In addition, the diffusing capacities of oxygen and, in particular, carbon dioxide increase dramatically with exercise, which facilitates their exchange

Describe the impact the following factors have on Stroke Volume -- End Diastolic Volume (EDV) -- Catecholamines -- Frank-Starling mechanism

EDV -- the volume of blood available to be pumped by the left ventricle at the end of the filling phase, or diastole. Catecholamines -- E/NE increase sympathetic activity, causing increase force of contraction which leads to more blood ejected from heart Frank-Starling mechanism -- A mechanism by which the stroke volume of the heart is increased by increasing the venous return (mm pumps, venoconstriction) of the heart leading to greater EDV which results in a more forceful contraction due to stretch of ventricles leading to greater cardiac emptying

Functional Overreaching (FOR) vs. Nonfunctional Overreaching (NFOR).

FOR: excessive training that leads to short-term decrements in performance -- Recovery from this condition is normally achieved within a few days or weeks of rest -- short-term overreaching followed by an appropriate tapering period can result in beneficial strength and power gains NFOR: When the intensification of a training stimulus continues without adequate recovery and regeneration -- results in stagnation and a decrease in performance that will continue for several weeks or months. Note: some athletes respond positively to overreaching strategies whereas for others, overreaching can be the catalyst for OTS.

Tidal Volume Level -- Define Anatomical and Physiological Dead Spaces

Physiological dead space refers to alveoli in which poor blood flow, poor ventilation, or other problems with the alveolar surface impair gas exchange Anatomical Dead Space - air occupies areas not functional for gas exchange in the respiratory passages: the nose, mouth, trachea, bronchi, and bronchiole

Systolic Blood Pressure vs Diastolic Blood Pressure

Systolic blood pressure estimates the pressure exerted against the arterial walls as blood is forcefully ejected during ventricular contraction (systole) Diastolic blood pressure is used to estimate the pressure exerted against the arterial walls when no blood is being forcefully ejected through the vessels (diastole)

Ventilatory equivalent for oxygen

The ratio between the volume of air expired or ventilated and the amount of oxygen consumed by the tissues in a given amount of time >>> During intense exercise, minute ventilation rises disproportionately to the increases in oxygen uptake and begins to parallel the abrupt rise in blood lactate.