question: Why is it physically difficult to start working out again after taking only a few days to a week off?
comment: Building muscle and endurance takes energy expenditures that the body would rather not spend, if it "thinks" it can avoid expending the energy. When you stop working out, the body starts trying to go back to a pre-workout "form" as it can use the muscle as an energy source and there's nothing indicating to it that this extra muscle is needed any more. The body "assumes" it's possible you'll face problems getting food in the near future and no longer spends energy on what it considers non-essential muscle. And over time, that will change from "not maintaining the increased muscle" to "cannibalize muscle" the longer the absence of exercise goes. As annoying as it is, the body would rather put energy storage into fat cells than muscle cells, so even if you're getting adequate food, it will try to put excess resources into fat.
passages: Prehab can be applied to people awaiting orthopaedic surgery. The intention is that the fitter they are when they have surgery the quicker they will recover from surgery. Massage and strengthening exercises are tailored to the patient so that even those with end-stage arthritis (bone on bone) can safely do some form of exercise and improve their outcome. Research evidence is still poor, but suggests that it improves quadriceps strength before knee surgery and hence the support of the knee joint post-surgery.
   "A couple of years ago I was told by a fitness trainer that an eight-week cycle of steroids could change my career. In his experience, a player that did just one cycle would maintain 60 per cent of the gains he achieved. To put this in perspective:
   Eccentric training is often associated with the terms "muscles soreness" and "muscle damage". In 1902, Theodore Hough discovered and developed the term DOMS (delayed onset muscle soreness), after he found that exercises containing negative repetitions caused athletes to have sore muscles. Hough believed this was causing a rupture within the muscle; when he looked further into the subject, he found that when performing eccentric exercise that exhibited soreness, the muscle "quickly adapts and becomes accustomed to the increase in applied stress". The result of this was that the muscles' soreness not only decreased, but the muscular damage did too.
   Physiotherapy is used extensively to help patients recover function after joint replacement surgery. A graded exercise programme is needed initially, as the patients' muscles take time to heal after the surgery; exercises for range of motion of the joints and ambulation should not be strenuous. Later when the muscles have healed, the aim of exercise expands to include strengthening and recovery of function.
  
  Section::::Materials.
   Background: The preoperative period (prehabilitation) may represent a more appropriate time than the postoperative period to implement an intervention. The impact of prehabilitation on recovery of functional exercise capacity was thus studied in patients undergoing colorectal resection for cancer.
   Section::::Mechanism.:Repeated-bout effect.
  
  After performing an unaccustomed eccentric exercise and exhibiting severe soreness, the muscle rapidly adapts to reduce further damage from the same exercise. This is called the "repeated-bout effect".
  
  As a result of this effect, not only is the soreness reduced, but other indicators of muscle damage, such as swelling, reduced strength and reduced range of motion, are also more quickly recovered from. The effect is mostly, but not wholly, specific to the exercised muscle: experiments have shown that some of the protective effect is also conferred on other muscles.
   Section::::Sports and rehabilitation.
  
  With eccentric training, muscles are able to create more for less work, which has special meaning in the realms of high performance sports — both for injury prevention and optimal-performance training. For athletes and sports enthusiasts, this eccentric model can help with explosive force
   It is important that hypermobile individuals remain fit - even more so than the average individual - to prevent recurrent injuries. Regular exercise and exercise that is supervised by a physician and physical therapist can reduce symptoms because strong muscles increase dynamic joint stability. Low-impact exercise such as closed chain kinetic exercises are usually recommended as they are less likely to cause injury when compared to high-impact exercise or contact sports.
  
  Heat and cold treatment can help temporarily to relieve the pain of aching joints and muscles but does not address the underlying problems.
  
  Section::::Treatments.:Medication.
   In addition, excessive training may cause exhaustion of the autonomic nervous system. Some symptoms include decreased total testosterone level, an imbalance between testosterone and cortisol, decreased sympathetic tone, and decreased exercise-induced lactate. These chemical balances can lead to premature osteoporosis, where the lack of testosterone accelerates bone loss, and elevated levels of cortisol alters calcium and bone metabolism by “increasing bone reabsorption and decreasing bone formation or intestinal absorption of calcium”. Calcium undernutrition may eventually occur, accelerating premature osteoporosis.
  
  Section::::Mechanisms.
   Active recovery is recommended after participating in physical exercise because it removes lactate from the blood more quickly than inactive recovery. Removing lactate from circulation allows for an easy decline in body temperature, which can also benefit the immune system, as an individual may be vulnerable to minor illnesses if the body temperature drops too abruptly after physical exercise.
  
  Section::::History.
   Section::::Muscle injury.
  
  Eccentric contractions are a frequent cause of muscle injury when engaging in unaccustomed exercise. But a single bout of such eccentric exercise leads to adaptation which will make the muscle less vulnerable to injury on subsequent performance of the eccentric exercise.
  
  Section::::Findings.
  
  Several key findings have been researched regarding the benefits of eccentric training:
  
  BULLET::::- Eccentric training creates greater force owing to the "decreased rate of cross-bridge muscle detachments." Patients and athletes will have more muscle force for bigger weights when eccentric training.
   Section::::Long-term effects.:Neuroplasticity.:Structural growth.
   Several studies show that markers of inflammation are reduced following longer-term behavioural changes involving both reduced energy intake and a regular program of increased physical activity, and that, in particular, IL-6 was miscast as an inflammatory marker. For example, the anti-inflammatory effects of IL-6 have been demonstrated by IL-6 stimulating the production of the classical anti-inflammatory cytokines IL-1ra and IL-10. As such, individuals pursuing exercise as a means to treat the causal factors underlying chronic inflammation are pursuing a course of action strongly supported by current research, as an inactive lifestyle is strongly associated with the development and progression of multiple inflammatory diseases. Note that cautions regarding over-exertion may apply in certain cases, as discussed above, though this concern rarely applies to the general population.
   "Eccentric actions place a stretch on the sarcomeres to the point where the myofilaments may experience strain, otherwise known as exercise induced delayed onset muscle soreness (DOMS)" (Aaron Bubbico & Len Kravitz, 2010). One area of research that has much promise in relation to DOMS and eccentric exercise is the repeated-bout effect (RBE). To help prevent or lessen DOMS from eccentric exercise, or to facilitate recovery from it, the exerciser would eccentrically stimulate the muscle then repeat at weekly intervals to build up strength and allow the strain (in response to a given force level) to reduce over time.
   Dr. Pope said that when individuals have a regular workout regimen, but sustain an injury, they can't wait to get back to working out and that it has a psychiatric protective effect for them. He also said their instincts are to get back to work and if they allow their working out to lapse too long then bad things may start to happen.
  
  Section::::Plot.:Steroids.
   The "Stamina" case, now both as a media phenomenon and scientifically, was analyzed and criticized by, among others, the Accademia dei Lincei, by Nature and by the European Medicines Agency. In May 2013, thirteen scientists published a critical analysis of the method in the EMBO Journal, highlighting their concerns about the inconsistency of scientific evidence, the methodological shortcomings and the lack of publications.
   Preventing overtraining is important for many athletes, who want to avoid taking time off to recover from overtraining. One method preferred by many collegiate and professional level athletes is the incorporation of active recovery into training. The gradual varying of intensity and volume of training is also an effective way to prevent overtraining. The athlete should be closely monitored by keeping records of weight, diet and heart rate and the training program should be adjusted in accordance to different physical and emotional stresses.
   Iron man (sports streak)
  
  An Iron man is an athlete of unusual physical endurance. This durability is generally measured by an athlete's ability to play without missing a game and/or start for an extended period of time, sometimes, even for an entire career. Some of the more notable athletes with significant streaks in sports history includes baseball's Lou Gehrig and Cal Ripken Jr., American football's Brett Favre and Joe Thomas, basketball's A. C. Green, ice hockey's Doug Jarvis, and stock car racing's Jeff Gordon.
  
  Section::::Background.
   BULLET::::- Eccentric contractions use less energy and actually absorb energy that will be used as heat or elastic recoil for the next movement.
  
  BULLET::::- Increased DOMS leads to more tenderness in eccentric, rather than pure pain or tendon swelling amongst patients.
  
  BULLET::::- Repeated-bout Effect markedly reduces DOMS. "Completing bouts of eccentric training and then repeating the workout 1 week (or more) later will result in less DOMS after the second workout."
  
  BULLET::::- Older individuals are less vulnerable to injury from eccentric exercise, primarily because of the reduced strain on muscle-tendon groupings as compared to traditional concentric exercise.
   A fall or torque to the leg during the first two months after surgery may jeopardize healing. Patients must exercise extreme caution during all activities, including walking, until healing is complete.
  
  After rehabilitation, preventing osteoarthritis involves slowing the progression and spread of the disease. Maintaining aerobic cardiovascular fitness has been an effective method for preventing the progression of osteoarthritis. Light, daily exercise is much better for an arthritic knee than occasional, heavy exercise.
   Plateau effect
  
  The plateau effect is a force of nature that lessens the effectiveness of once effective measures over time. An example of the plateau effect is when someone's exercise fails to be as effective as in the past, similar to the concept of diminishing returns. A person enters into a period where there is no improvement or a decrease in performance.
  
  Section::::Overview.
   Section::::Health effects.:Cardiovascular fitness.:Cardiovascular disease.
  
  A 2015 meta-analysis comparing HIIT to moderate intensity continuous training (MICT) in people with coronary artery disease found that HIIT leads to greater improvements in VO max but that MICT leads to greater reductions in body weight and heart rate. A 2014 meta-analysis found that the cardiorespiratory fitness, as measured by VO max, of individuals with lifestyle-induced chronic cardiovascular or metabolic diseases (including high blood pressure, obesity, heart failure, coronary artery disease, or metabolic syndrome) who completed a HIIT exercise program was nearly double that of individuals who completed a MICT exercise program.
  
  Section::::Health effects.:Metabolic effects.
   Section::::Long-term effects.:Mechanism of effects.:IGF-1 signaling.
   Traditionally, strength training (the performance of exercises with resistance or added weight) was not deemed appropriate for endurance athletes due to potential interference in the adaptive response to the endurance elements of an athlete's training plan. There were also misconceptions regarding the addition of excess body mass through muscle hypertrophy (growth) associated with strength training, which could negatively effect endurance performance by increasing the amount of work required to be completed by the athlete. However, more recent and comprehensive research has proved that short-term (8 weeks) strength training in addition to endurance training is beneficial for endurance performance, particularly long-distance running.
   Like pharmacological drugs, physical exercise may be chemically addictive. Addiction can be defined as the frequent engaging in the behavior to a greater extent or for a longer time period than intended. It is theorized that this addiction is due to natural endorphins and dopamine generated and regulated by the exercise. Whether strictly due to this chemical by-product or not, some people can be said to become addicted to or fixated on psychological/physical effects of physical exercise and fitness. This may lead to overexercise, resulting in the "overtraining" syndrome.
  
  Section::::Mechanism.
  
  A number of possible mechanisms for overtraining have been proposed:
  