The Often Forgotten Basics of Strength and Conditioning and Rehabilitation

In the realm of high performance, rehabilitation, and musculoskeletal health, it is easy to get caught up in new modalities, technologies, or the latest trends. Did someone say Hybrid Athlete, red light therapy, or cold plunge?

Regardless of whether you’re an elite athlete, high-functioning business person, a busy parent, or an aging adult striving to maintain your independence, it’s important to invest in the approaches that move the needle the most when it comes to improving your health and performance. These secondary modalities (see cold plunge and red-light therapy above), are great but unless you’re absolutely nailing the basics, these “one percenters”, as I call them, aren’t going to make up for a lifestyle of sedentary behaviour or lack of consistency with your nutrition, training and sleep.

This week I wanted to talk about some of the foundational principles of exercises training. While my personal practice includes both programming for people with unique and individualized goals as well as programming for injury rehabilitation, the principles of load progression largely remain the same. Unfortunately, these principles can be underappreciated in the rehabilitation and performance space, as well as in folks who are just looking to maintain a healthy lifestyle.

Luckily, these principles of training have remained relatively constant over the years and are backed by significant research in sports physiology, tissue re-modelling, metabolic health and psychological well-being. These principles form the bedrock of effective, sustainable, and safe training programs. So, whether you’re a clinician, coach, educator, athlete or weekend warrior, this week’s newsletter is for you.

Among the most central frameworks are the FITT principle (Frequency, Intensity, Time, and Type), the SAID principle (Specific Adaptations to Imposed Demands), and the concept of progressive overload. When understood and applied correctly, these principles help optimize training adaptation and recovery, prevent injury, build tissue resilience, and avoid the deleterious effects of overtraining and burnout.

The FITT Principle: Structuring the Dose

The FITT principle was originally developed in the context of cardiovascular health and physical activity promotion, but it has since been adopted across the spectrum of rehabilitation, strength and conditioning, and athletic performance. FITT is an acronym for Frequency, Intensity, Time, and Type, and serves as a framework for organizing and manipulating the dosage of physical activity in a structured and measurable way.

Frequency refers to how often a person engages in training stimuli within a given timeframe. This variable plays a major role in recovery dynamics, training adaptations, and risk modulation. For example, training frequency affects how neuromuscular systems recover and adapt, especially when multiple modalities (e.g., resistance, plyometrics, aerobic conditioning) are concurrently programmed.

Intensity, often described in terms of percentage of maximal capacity (e.g., 1RM for strength or VO₂max for endurance), is one of the most critical variables in driving adaptation. It influences the recruitment of larger motor units, the mechanical stress placed on tissues, and the degree of systemic and neurological fatigue generated. From a neurophysiological standpoint, intensity also governs hormonal responses, central nervous system arousal, and adaptation thresholds.

Time encompasses the total duration of a training session or the specific duration spent in various exercise domains (e.g., time under tension in resistance training or interval time in aerobic work). It directly interacts with both frequency and intensity to modulate total training volume and energy system demands.

Type refers to the modality of exercise, such as resistance training, sprinting, swimming, or mobility work. It determines the primary physiological systems stressed and, as such, must align with the athlete’s goals, current needs and recovery status. The FITT framework is invaluable in both performance and clinical contexts because it offers a systematic way to scale, progress, or regress a program while maintaining control over key training variables.

The SAID Principle: Specificity Drives Adaptation

The SAID principle—Specific Adaptations to Imposed Demands—is a basic principle of exercise physiology. It assumes that a biological system (e.g., us) adapt specifically to the demands and environment it’s exposed to upon. In other words, the body responds in a manner that is specific to the type, intensity, and direction of stress it encounters. It takes effect in the presence of load, but also negatively in the absence of load.

For example, tendon tissue adapts differently to high-load, slow-velocity training compared to low-load, high-velocity activity. We can see this in the microscopic tissue characteristics of tendons. Similarly, maximal strength training induces neural and muscle changes that endurance training simply cannot replicate. This is why sprinters must sprint to improve top-end velocity, and long-distance runners must accumulate time in target aerobic zones to enhance oxidative capacity.

Importantly, adaptation in the opposite direction also occurs. For example, tendon, muscle and the cells within these tissues change in the absence of stimuli and load. The same can be said of a nervous system that is starved of inputs.

From a rehabilitation, return-to-play and performance standpoint, the SAID principle is extremely important. Misapplication of this principle often leads to either under-training (i.e., insufficient stimulus to provoke adaptation) or over-generalization (e.g., focusing on non-specific tasks that fail to transfer to the desired activity). Applying the SAID principle correctly ensures that training the stress is relevant, targeted, and effective, especially in cases where sport- or task-specific loading is required, like in specific sports. You can’t expect to improve at tennis if you’re training for ice hockey.

Progressive Overload: The Heart of Adaptation

While specificity governs the direction of adaptation, progressive overload governs its magnitude and continuation of adaptation. Without a gradual increase in workload, the body has no impetus to further adapt, and performance may plateau. Progressive overload can be achieved through increasing load (e.g., weight lifted), volume (e.g., sets or reps), density (e.g., more work in less time), or complexity (e.g., biomechanical difficulty).

This principle underpins muscular hypertrophy, strength development and aerobic capacity. However, the application must be calibrated and be – as stated – progressive. Progression that is too quick or aggressive can lead to excessive fatigue or injury. On the other hand, progression that is too conservative may fail to stimulate meaningful change, leaving us short of our end goal.

For tissues like tendons, cartilage and bone that adapt relatively slowly to mechanical load, overload must be introduced incrementally. Tendons respond best to loads that evoke sufficient strain without exacerbating pain or discomfort. Similarly, bones require exposure to weight-bearing or higher-impact activity and directional loading to maintain bone mineral density. Sports like swimming and cycling won’t stimulate bony changes in the same way that running or plyometrics will.

Adaptations in all tissues are all load-dependent and adhere to the dose-response relationship (pending adequate recovery) that is at the heart of progressive overload.

Overreaching vs Overtraining: What Happens When We Do Too Much?

When we’re training and attempting to adhere to the above-described principles, it’s important to understand and be able to distinguish between different parts of the spectrum towards overtraining. On one hand we need to push ourselves to our limits in order to strain various systems and break through training barriers. On the other hand we need to be cognizant of our physiological limits to remain energized and injury free. Athletes walk a fine line as training loads can often be extremely high, and therefore the recovery need is also high. This leads us to two important terms and concepts: overreaching and overtraining—two concepts that exist on the same physiological continuum but differ vastly in outcome.

Functional overreaching (FOR) is a short-term training strategy where athletes intentionally exceed their recovery capacity. This is about breaking through barriers. Pushing the envelope. This results in transient fatigue and temporary performance decrements, but—when followed by adequate rest and nutrition—leads to what we call a supercompensation and an abrupt improvement in performance. This strategy is frequently used in elite athletes and is a legitimate part of periodization when applied correctly prior to a big competition or race.

However, when the stimulus is too great or the recovery time is insufficient, FOR can transition into non-functional overreaching (NFOR), characterized by longer-lasting performance declines with no subsequent performance gains. If this state persists and you don’t get the recovery necessary, it may progress to overtraining syndrome (OTS). This is a condition that effects all domains of who we are from physical to mental and everywhere in between. It often involves chronic fatigue, mood disturbances, autonomic dysregulation, hormonal imbalances, weight loss or gain and impaired immune function. Recovery from OTS can take months and may derail an athlete’s season or career.

Monitoring training load, subjective wellness, and objective metrics such as resting heart rate, heart rate recovery, body temperature and heart rate variability can be important in picking up early signs of NFOR, in hopes of preventing a further decline into OTS. Overtraining is not merely a function of just training volume; rather, it reflects a mismatch between stress and recovery. Coaches and clinicians and those of us who train consistently and with high intensity, must be proactive in recognizing the signs of NFOR and adjust programming accordingly.

Recovery and the Adaptation Process

Adaptation is not created during the stressor itself but in the recovery period that follows. Inadequate recovery undermines even the most well-designed training program. Recovery encompasses more than rest; it includes nutritional support, sleep hygiene, parasympathetic reactivation, and psychological stress regulation. From a physiological standpoint, the body's capacity to adapt is dependent on how well we recover.

Incorporating structured de-load weeks and monitoring subjective and objective fatigue are all essential for maintaining long-term progress. Periodization models that cycle volume and intensity ensure that recovery is built into training, not just treated as an afterthought.

Applying These Principles Across the Lifespan for Longevity

While these principles are often applied in athletic or performance settings, they are equally crucial in the context of healthy aging. As we age, we experience anabolic resistance, sarcopenia, decreased neural drive and neuromuscular control—all of which can be mitigated through properly dosed exercise and resistance training. The same training principles apply: tissues must be challenged, recovery must be prioritized, and the stimulus must be specific to the individual’s goals.

For older adults, maintaining muscle mass, joint integrity, and neuromuscular coordination is essential for fall prevention, cognitive health, and independence. By applying the same foundational principles—FITT, SAID, and progressive overload—within age-appropriate frameworks, we can promote longevity, live better and reduce the burden of non-communicable diseases on our healthcare systems.

Conclusion

Since their inception, the foundational principles of exercise prescription have remained largely constant. The FITT principle structures the dosage; the SAID principle ensures the relevance of adaptation; progressive overload drives improvement; and strategic recovery enhances and preserves it. These are not abstract theories—they are the physiological laws that have been supported time and time again in the research.

As a sports and performance health professional, I have a responsibility to apply these principles to my patients while educating them on why they’re important. Being mindful of the principles discussed above is what separates an evidence-informed, progressive program from a random selection or exercises that “seem right”.

As someone reading this, I will safely assume you are interested in maintaining a healthy balance of exercise as you continue to age. I want to reiterate that these principles are not just for the elite athlete or someone highly dedicated to weight lifting. These principles are relevant for all of us as they will keep us doing the things that we value most.

Yours in good health,

Andrew

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