Kinesiology For Dummies
Being physically active and training for fitness and performance can seem pretty complex when you consider all the factors involved: mechanical loads and forces applied, energy metabolism, musculature and bone health, and so on. Kinesiologists study these areas to help athletes and others improve athletic performance, enhance mobility, and avoid or heal from injury, but anyone can apply the basic principles of kinesiology. These articles touch on some simple changes that occur as a result of aerobic training, explain the energy systems needed for different kinds of physical activity, and provide guidelines for effective strength training and stable movement, and highlight a strategy for evaluating movement.
6 Ways Aerobic Training Strengthens the Cardiovascular System
Exercise is a fantastic medicine for the body, especially for your heart. When you engage in aerobic training, your cardiovascular system becomes fit. Consistent aerobic activity produces physical changes in the heart, the blood vessels, and in your ability to use oxygen. It’s like getting a complete overall to a car’s engine! Just look at all of the changes:
Resting heart rate is lower after aerobic training. The lowering of the heart rate is due to two primary factors:
The parasympathetic nervous system becomes more dominant at rest, producing a slower resting heart rate. Also, your heart rate returns to its resting rate more quickly after a workout.
The size of the heart chamber grows, meaning it takes fewer heart beats to pump the same amount of blood.
Blood pressure decreases. Exercise, especially moderate aerobic exercise, can lower resting blood pressure in people with high blood pressure. In some cases, it may lower blood pressure as much as 10 mmHg!
Stroke volume increases. Long-term aerobic training helps enlarge the ventricles and strengthens the heart muscle. Because a stronger heart muscle can pump out more blood, these changes result in a larger volume of blood pumped with each stroke. At submaximal work rates, the heart rate is lower because fewer beats are needed to produce the same cardiac output.
Peak cardiac output increases. Cardiac output represents total blood flow through the heart each minute. If you can pump more blood, you can work harder! Because stroke volume is higher, your maximal work output will be greater.
More blood vessels form. The density of capillaries in the muscles increases, meaning more oxygen can be delivered to the muscle. Just as laying more water lines can improve irrigation of a farm field, aerobic training can an increase the irrigation of the muscle. In addition, blood vessels that were previously dormant begin to open and move blood.
You’re better able to tap into and use more of the oxygen carried in the blood. This improvement is due to the increase in the size and number of mitochondria (and the enzymes contained within), which draw oxygen from the blood, and to the increased availability of the oxygen as a result of the many blood vessels.
All these changes happen at the same time, which no single medication can achieve. Exercise is the best medicine for changing your body to become fit and to be able to do more work!
3 Ways the Body Produces Energy to Fuel Metabolism
ATP, which stands for adenosine triphosphate, is the sole source of energy for all human metabolism, yet very little of this fuel is actually stored in the body. Instead, the body has three different systems of ATP production: ATP-PC, anaerobic glycolysis, and aerobic phosphorylation.
Each system uses different starting fuels, each provides ATP at different rates, and each has its own downside (like fatigue). These differences mean that each method of energy production is best suited for particular kinds of activities.
The following table outlines the key characteristics of the body’s different ATP-producing methods.
|ATP-PC||Anaerobic Glycolysis||Aerobic (Oxidative) Phosphorylation|
|Description||Provides ATP at a very fast rate. Your body holds limited stores of ATP-PC.||Provides ATP fast, but not as fast as ATP-PC.||Provides ATP at a slower rate than the other systems, but is great for endurance activities.|
|Starting Fuel||Phosphocreatine (PC) stored in the sarcomere. PC combines creatine and phosphate by using high-energy bonds.||Glucose stored in the muscle and liver in a concentrated form called glycogen. Glucose can be taken from muscle glycogen or transported from the blood via the liver.||Fats, carbohydrates, and proteins.|
|How Energy Is Produced||The chemical bonds that hold creatine and phosphate together are broken, a process that releases energy that can remake new ATP.||Enzymes in the cells convert glucose into lactic acid, producing ATP. Although ATP is needed to get glucose into the cell, you ultimately produce double the amount of ATP.||Fats and carbohydrates are delivered to the mitochondria and broken down to yield ATP. The waste product of a hydrogen ion (H+) is bonded to oxygen to form water. The other waste product is carbon dioxide (CO2), which can be breathed off.|
|Amount of Energy Produced||Enough for about 10 seconds of very high-intensity exercise. Total amount depends on stores of PC and enzymes to convert it to ATP.||Enough to power heavy exercise for extended periods (2 minutes or more). The amount depends on the availability of glucose and enzymes needed for energy production, and the levels of lactic acid.||The amount depends on enzymes, the availability of oxygen to the mitochondria, and the availability of carbohydrates and fats. With training, high levels of intensity for very long periods of time are possible (running a marathon at a 5 min/mile pace, for example).|
|Used Most for Activities Like||100-meter sprint, short sprint, high jump, swinging a bat.||Intense activities lasting under 3 minutes, or during short bouts of heavy work.||Long-duration, low-to-moderate–intensity activities, like walking, jogging running, hiking, and swimming.|
|Cost or Tradeoff||When you run out of PC, you slow down or weaken.||Lactic acid builds up and causes the muscles to fatigue; it also shuts down glycolysis.||Work intensity is lower; running pace can’t be as fast as a sprint. Altitude or another condition that limits available oxygen (mountain climbing above 5,000 feet, for example) reduces performance.|
|How Training Maximizes these Fuel Sources||Increases stores and enzymes to make ATP faster.||Increases stores of glycogen and enzymes to make ATP faster and to better neutralize lactic acid.||Increases size and number of mitochondria and the number of enzymes to make ATP.|
4 Simple Rules for Gaining Strength and Muscle
A variety of methods exist for strength training, yet many people train the wrong way and unwittingly sabotage their efforts to increase strength and muscle mass. To see the fitness results you are looking for, make sure your strength-training regimen incorporates these four simple rules.
Rule #1: Lift heavy enough
If you want to make your muscles stronger, you must force them to do work more than they are used to (called overload)! To gain strength, you need to actually cause micro damage to the muscle by using a load that the muscle isn’t accustomed to.
As a general rule, you need to lift a load that is about 60 percent of your one repetition max (IRM), the heaviest load that you can lift just one time. If your 1RM is 100 pounds, for example, you must work out with at least 60 pounds.
Eccentric contractions (when the muscle lengthens while contracting — like when you lower a weight during a biceps curl) seem to cause the most trauma to the muscle during weightlifting. But the upside is that this trauma is the stimulus for building muscle. So rather than letting your arms drop after a lift, lower the weights in a controlled manner. Doing so lets you work the muscle during that phase of the movement.
Rule #2: Lift to fatigue
If you lift a single load, even one that’s heavy enough to damage the muscle, you haven’t stressed all your muscles. Here’s why: As more muscle fibers become fatigued, your body calls up even more fibers to help the fatigued ones carry the load. That’s why you must keep lifting to ensure that you’re stressing your muscles sufficiently. Only when all your muscle fibers are fatigued have you worked the entire muscle and stimulated growth.
Rule #3: Eat and rest to let your muscle recover
Muscles grow during the recovery time between workouts. So recovery is very important to ensure muscle growth. To make sure your recovery period maximizes muscle growth, you need rest, carbohydrates, and protein. Follow these guidelines:
Include adequate carbohydrates in your diet. To fuel the growth of new muscle tissue, carbohydrates should make up 50 percent to 60 percent of your diet.
Eat adequate amounts of protein. Protein helps form muscle. You should have between 0.4 and 0.6 grams of protein per pound of body weight. A 180-pound man, for example, needs 90 grams of protein per day (180 × 0.5 g/lb = 90 grams).
Sleep! Restful sleep is the time when the hormones of muscle growth (growth hormone and testosterone) are highest.
The harder the work, the more recovery you need. The more overload you give your muscles, the more recovery they need. Usually 24 to 48 hours between workouts is enough.
Rule #4: Progressively increase the load as the muscle adapts
You need to add more load when you can easily do more repetitions than you’re used to. If, for example, you choose a weight that is 60 percent of your 1RM (which equals about 15 to 20 repetitions before fatigue) and you have adapted enough that you can lift the weight 23 times, it’s time to add more load.
The amount of the increase varies and depends on the size of the muscle. Should you increase five pounds, ten pounds, or something more? A better strategy is to increase by a percent of the load so that the loads across different muscle groups are standardized. A 10 percent increase should be enough to provide a nice progression.
2 Mechanisms That Stabilize Your Body's Joints to Avoid Injuries
Maintaining physical stability takes more than a single structure working in isolation to provide joint support. Instead, lots of parts — muscles, tendons, ligaments, bones, and other soft tissues — all have to work together to produce a stable joint. Stable joints help you avoid injury, such as shoulder dislocations and ACL sprains.
The factors that help maintain stability are usually broken up into separate categories: the active mechanisms (the muscles) and the passive mechanisms (pretty much everything else, like the ligaments, bone shapes, cartilage, joint capsule, and so on). The components from each type of mechanism must communicate with each other to provide stability.
If the muscles (active restraints) don’t fire as they should or are weak, stability is compromised, and if the ligaments, tendons, and so on (passive restraints) have been compromised, injury may result as well. Someone who has had strength issues in the muscles or who has suffered from a previous ligament injury is at increased risk for injury.
The active restraint mechanism
The active restraint mechanism (the muscles) is the contractile component of joint stability. These muscles act on and around a particular set of structures (your joints). Not only do you rely on the muscles that act on a joint to provide the forces needed to move or propel objects, but you also rely on them to resist forces that could potentially cause injury.
Here’s how the active restraint mechanism works:
Sensory information is continually being collected from around the joints involved in an activity.
This information includes things like how fast you want to go, whether you’re traveling up or down hill, whether the ground is uneven or smooth, and so on.
Depending on your ability to retrieve this sensory information, the muscles adapt accordingly.
Problems arise when a muscle or group of muscle is weak or isn’t able to interpret the information it receives in a timely manner. In this situation, the movement pattern is thrown off, compromising stability.
The passive restraint mechanism
The structures that make up the passive restraint mechanism don’t contract and consist of structural restraints (like ligaments, cartilage, bone shape, and so on) and components — called mechanoreceptors — whose job it is to detect neurological information. Mechanoreceptors are specialized sensory organs that respond to mechanical stimuli, such as tension, pressure, and displacement. Together, both the structural components of the passive restraint mechanism and the mechanoreceptors enable your body to collect the information it needs related to movement.
The mechanoreceptors are found in muscle, tendons, bone, ligaments, and other soft tissues. When these structures are affected by an activity, the information is shared and either triggers a reflex response or causes the brain to create a new motor plan.
Because these receptors have to be physically changed to respond, they are susceptible to injured tissue. To understand this, imagine that you sprained a ligament in the past. Now, as a result of that sprain, your ligament is a bit longer. The next time you stumble, your ankle will actually twist farther before the mechanoreceptor is activated and recognizes the situation.
The 5 Stages of Motion Analysis
Motion analysis is a fancy way to refer to the act of evaluating how someone one moves. Coaches, physical fitness trainers, physical therapists, and others use motion analysis to help their patients and clients enhance mobility and improve performance. Knowing where to start can be difficult, but if you break the analysis down into five stages, you’ll be well on your way!
Stage 1: Knowing the nature and objective of the motion
To begin movement analysis, the examiner (coach, clinician, personal trainer) must have some background knowledge about the task to be completed. Understanding what the performer is trying to accomplish and knowing the components needed to be successful are essential to the analysis. Background knowledge helps you identify the key elements of the movement that need focus.
Stage 2: Breaking the movement up into clear phases
To make sense of what you are seeing, you break the movement up into segments or phases. Complex movements all require preparation, execution, and follow-through components. Within each phase is a series of movements that need to occur for the next phase to follow and/or be successful.
For example, when you perform a squat, you start in a standing position and then squat down. But to squat down, you need to bend your hips, then knees, and finally your ankles, all while keeping your back straight. To come back up, you do the reverse in a timely and coordinated way. In this case, someone analyzing these motions would break the squat into two phases, the down (return) and up (power) phases.
Stage 3: Noting the preparation position
At this stage of the analysis, you note the patient’s or client’s preparation position. Getting into a position that facilitates the impending movement is the key to this phase. To jump, for example, you need to bend at your hips, knees, and ankles. This action represents the preparation phase of a standing long jump. By achieving a proper preparation position, the performer is able to facilitate the strength, speed, and efficiency of the task.
Stage 4: Providing evaluation and diagnosis
Ultimately the purpose of the motion analysis is to correct or improve the performance or avoid injury. To do this, you evaluate the subject’s performance of the actual task. Based on your findings, you can identify specific flaws and make diagnoses. For example, you may note that someone is limping when he walks. By noting where within the walking pattern he has a flaw, you can determine what the problem is (perhaps he isn’t striking the ground with his heel as he should) and identify how to correct it.
The evaluation process usually involves a comparison of the pre-defined critical factors. If you find that the performer repeatedly falls outside of the normal range, you note it during this stage.
Stage 5: Providing intervention and feedback
Saying what is wrong with someone’s motion is usually easy; figuring out how to correct it is a bit more challenging. To perform this final step in, you must have very good knowledge of the task at hand and be able to focus in on relevant information from the client or patient (strength, injury, and performance) and his goals. Based on what you know about the patient, you can prioritize the feedback you give.