The Tribune

By DR KENT L BAZARD

Sports Medicine Physician

“DOC, how long before I’m fit again?”

It is one of the most common questions I hear, particularly at this time of year. Athletes are returning to structured training after summer breaks, younger athletes are discovering that the first few sessions back feel considerably harder than expected, and adults are returning to the gym with their own versions of the same question: “How long will it take me to lose 20 pounds?” “How long before I start looking different?” or simply, “How long before I feel in shape again?” The frustrating but scientifically correct answer is: it depends.

The first problem is that “getting in shape” is not one physiological process. Cardiovascular fitness, muscular strength, muscle size, power, speed, flexibility, body composition and sport-specific conditioning are all different qualities, and they adapt at different rates.

A person may become noticeably stronger before they look more muscular. An athlete may regain endurance while still lacking their previous speed. Someone attempting to lose weight may become considerably fitter even though the number on the scale has barely changed.

Cardiovascular fitness is one of the qualities that can begin responding relatively quickly. Within the first several weeks of regular aerobic training, the cardiovascular system starts becoming more efficient. Plasma volume can increase, stroke volume improves, mitochondrial enzymes become more active, and working muscles become better at extracting and utilizing oxygen.

Over subsequent weeks, changes in capillary density, mitochondrial function and cardiac efficiency contribute to improvements in VO₂ max and endurance. This is why someone who is completely exhausted after their first few runs may be surprised by how different the same workout feels a month later.

Strength follows a somewhat different pattern. During the first few weeks of resistance training, much of the improvement is neurological rather than the result of dramatically larger muscles. The brain and spinal cord become better at recruiting motor units, coordinating muscle activity and producing force.

In simple terms, you learn to use the muscle you already have more effectively. Structural changes within muscle become increasingly important as training continues.

The American College of Sports Medicine’s updated 2026 position stand, drawing on 137 systematic reviews involving more than 30,000 participants, confirms that progressive resistance training improves strength, muscle size, power and physical function. This explains something I frequently see with returning athletes. They may look physically similar to how they looked before their break, but the first few sessions feel terrible. Their timing is slightly off, movements do not feel as explosive, and repeated efforts become difficult much sooner. They have not suddenly lost all their muscle.

What has changed is the integration between the cardiovascular system, nervous system, energy systems and sport-specific movement patterns. Power and speed deserve particular attention because they are not simply products of strength. Power requires the athlete to produce force rapidly.

Sprinting, jumping, throwing and changing direction depend upon neural recruitment, rate of force development, tendon stiffness, coordination and technical efficiency. This is why an athlete returning from a layoff should not immediately attempt to reproduce the fastest sprint, highest jump or heaviest lift from the previous season. The capacity may return relatively quickly, but the tissues and nervous system still need progressive exposure to those demands.

Fat loss operates on another timeline altogether. People frequently ask how many weeks it will take to lose a specific amount of weight, but the scale cannot tell us exactly what tissue is being lost. Body weight includes muscle, fat, water, glycogen, bone and gastrointestinal contents. Rapid changes during the first week of a diet are therefore often partly changes in glycogen and water rather than dramatic fat loss.

Sustainable fat loss requires an appropriate energy deficit while preserving adequate nutrition and, ideally, resistance training to protect lean tissue. The objective should not simply be to make the scale move as quickly as possible. It should be to improve body composition while preserving health, muscle and performance.

The other side of this discussion is detraining: how quickly do we lose the fitness we worked so hard to build? Unfortunately, some adaptations begin declining surprisingly quickly. Aerobic conditioning appears particularly sensitive to complete inactivity. Research in endurance-trained athletes has demonstrated measurable reductions in VO₂ max, exercise time to exhaustion and maximal stroke volume after only two weeks of detraining. This does not mean an athlete becomes completely unfit in 14 days, but it demonstrates that the cardiovascular system begins adjusting when the training stimulus disappears.

Strength tends to be more resistant to short breaks, although the response depends on training history, age, activity level and how complete the cessation of exercise is. An athlete who stops formal training but continues swimming, running, playing basketball or lifting occasionally is very different from someone who becomes almost completely inactive. The practical lesson is important: you do not necessarily need to maintain peak training throughout a vacation or off-season, but maintaining some appropriate stimulus can significantly reduce the amount of rebuilding required later.

There is also good news for previously trained athletes. Returning to fitness is not necessarily the same as building it for the first time. Previous training leaves adaptations within the neuromuscular system and skeletal muscle, which helps explain the phenomenon commonly called “muscle memory.”

Technique also matters. A trained sprinter has already learned how to sprint, just as an experienced swimmer has established movement patterns that a beginner has not. Those qualities may become rusty, but they are not equivalent to starting from zero. This brings us to one of the biggest mistakes people make when getting back into shape: trying to resume training exactly where they stopped.

Your mind remembers what you used to be able to do. Your tissues may not yet be ready to do it. The first few weeks back should therefore be progressive. Instead of immediately chasing previous personal records, re-establish consistency.

For someone returning to resistance training, two or three well-designed sessions per week may initially be more productive than attempting six. The latest ACSM evidence supports progressive resistance training at least twice weekly for strength development, with the exact prescription depending on the desired adaptation. Heavier loading tends to favour maximal strength, greater weekly volume supports hypertrophy, and moderate loads moved rapidly can be useful when power is the objective.

For athletes, I generally prefer to rebuild in layers. First restore movement quality, range of motion and basic work capacity. Then progressively increase training volume. Intensity can follow as the athlete demonstrates that the body is tolerating the workload. Speed athletes should gradually reintroduce maximal-velocity running rather than going from no sprinting to repeated 100-percent efforts.

Throwing athletes should progressively rebuild throwing volume and intensity. Basketball and football players should reintroduce acceleration, deceleration and change-of-direction work before expecting the body to tolerate repeated maximal efforts.

Scheduling matters as much as exercise selection. Hard sessions should not simply be stacked together because an athlete is anxious to get fit quickly. Adaptation requires alternating stress with recovery. A difficult lower-body strength session followed immediately by maximal sprinting, followed by hard conditioning the next day, may produce plenty of fatigue without producing the quality of work we actually want.

Training should have a purpose: some days develop strength, others speed, aerobic conditioning, mobility, skill or recovery. More training is not automatically better training.

Nutrition determines how effectively the body responds to all of this work. Protein provides the amino acids required for tissue repair and remodeling.

For healthy exercising individuals, the International Society of Sports Nutrition supports approximately 1.4 to 2.0 grams of protein per kilogram of body weight per day for most athletes and active adults, with individual needs influenced by training and total energy intake. Spreading high-quality protein across the day is generally more useful than consuming very little throughout the day and attempting to compensate with one enormous meal at night.

Carbohydrate is equally important, particularly for athletes. Muscle glycogen fuels high- intensity exercise, repeated sprinting, resistance training and prolonged sport. An athlete who dramatically restricts carbohydrates while simultaneously increasing training volume may find that sessions deteriorate, recovery becomes slower and perceived effort increases.

Foods such as rice, potatoes, oats, fruit, whole grains and other carbohydrate sources should be matched to the athlete’s training demands rather than automatically eliminated in pursuit of weight loss.

After training, think about three things - replace, repair and rehydrate. Replace carbohydrate used during the session, provide sufficient high-quality protein for muscle repair, and replace fluids and electrolytes lost through sweat. A recovery meal does not have to be complicated. Rice with chicken and vegetables, potatoes with fish and salad, Greek yogurt with fruit and oats, or eggs with toast and fruit can accomplish the job.

For the athlete training again later that day, recovery nutrition becomes even more important because the window available to restore glycogen and fluid is much shorter.

Sleep may be the most underused performance supplement available. Training provides the stimulus; recovery allows adaptation. Poor sleep can interfere with training quality, appetite regulation, reaction time, mood and recovery. An athlete who trains perfectly for two hours but sleeps poorly and under-eats for the remaining 22 hours should not be surprised when progress is slower than expected.

At Empire Sports Medicine & Performance, this is why we try to move the conversation away from “How quickly can I get in shape?” toward a more useful question: “What adaptations does this individual need, and what is the safest and most efficient way to produce them?” We can assess strength, power, cardiovascular conditioning, range of motion, body composition, movement quality, previous injuries and sport-specific demands, then build the training and nutritional strategy around what the athlete actually needs.

So, how long does it take?

You may feel different within a few weeks. Meaningful cardiovascular and strength improvements can develop over several weeks of consistent training. Visible changes in muscle and body composition usually require longer. Major athletic transformation should be thought of in months and years rather than days. And if you stop training completely, some of the adaptations - particularly aerobic conditioning - can begin declining within a surprisingly short period. There is no universal 30-day answer because biology does not work according to marketing deadlines. Age matters. Genetics matter. Previous training matters. Nutrition, sleep, stress, illness, injury and consistency all matter.

The encouraging part is that the human body is extraordinarily adaptable. Give it the right stimulus, enough fuel, adequate recovery and sufficient time, and it will change.

Perhaps the real secret to getting in shape is therefore much less exciting than people want it to be. You do not need the perfect four-week challenge. You do not need to destroy yourself during every workout. And you certainly do not need to make up for months of inactivity in your first week back. You need a good plan, progressive training, appropriate nutrition and enough patience to allow physiology to do its job.

Getting fit takes time. Staying fit takes consistency. And getting back into shape starts by accepting that you cannot rush adaptation, but you can train intelligently enough to make every week count.