Quiz I Dr. Hahesy Fall 2012

Muscular Strength and Endurance Muscular strength is the amount of force a muscle can produce with a single maximum effort –Muscular strength is usually assessed by measuring the maximum amount of weight a person can lift one time (1 RM) Muscular endurance is the ability to resist fatigue while holding or repeating a muscular contraction –Muscular endurance assessed by counting the maximum number of repetitions of a muscular contraction a person can perform to fatigue Well-developed muscles can assist with: Daily routines Protection from injury Enhancement of your overall well-being

Basic Muscle Physiology Muscles consist of individual muscle fibers (cells) connected in bundles Muscle fibers are made up of smaller protein structures called myofibrils Proper strength training causes individual fibers to increase the number of myofibrils, resulting in hypertrophy Inactivity can reverse this process, resulting in atrophy

Skeletal Muscle Tissue

Slow and Fast Twitch Muscle Fibers Slow-twitch fibers are: Fatigue resistant Don’t contract as rapidly and forcefully as fast-twitch fibers Rely primarily on the aerobic energy system Fast-twitch fibers: Contract rapidly and forcefully Fatigue more quickly than slow-twitch fibers Rely more on the anaerobic energy system

Static vs. Dynamic Strength Training Static (isometric) exercise involves a muscle contraction without a change in the length of the muscle or joint angle An example is ‘pushing against a brick wall’ Considered useful in strength building after an injury/surgery Isometric contractions are usually held for 6 seconds Dynamic (isotonic) exercise involves a muscle contraction with a change in the length of the muscle- Two types Concentric contraction- muscle shortens as it works Eccentric contraction- muscle lengthens as it works

Do You Need Supplements? Supplement manufacturers often make claims about their products that will promote or enhance sport performance or physique Most of these substances are ineffective and expensive, as well as possibly dangerous Before purchasing and using these products, find other resources that document these dietary aids

What is Flexibility? Flexibility is the ability of a joint to move through its normal range of motion It is a highly adaptable fitness component and responds well when utilized as part of a fitness program Flexibility is joint specific, meaning that you must work all major joints, not just a few

Types of Flexibility There are two types of flexibility Static Flexibility: ability to hold an extended position at one end in a joint’s range of motion Dependent on your ability to: tolerate stretched muscles, joint structure, and tightness of connective tissues Dynamic Flexibility: ability to move a joint through its range of motion with little resistance Important for daily activities and sports

What Determines Flexibility? The flexibility of a joint is affected by the following: Joint Structure (cannot be changed) Muscle Elasticity and Length The Nervous System

Types of Stretching Techniques Static Stretching- slow and steady Ballistic Stretching- bouncing at the end of stretch Dynamic (Functional) Stretching- sport specific Proprioceptive Neuromuscular Facilitation (PNF)- partner assisted Passive- hold your stretch against resistance or force Active Stretching- hold your stretch with just your antagonist muscle as resistance

Managing Low-Back Pain More than 85% of Americans experience back pain at some time in their lives Lower-back pain is the second most common ailment in the United States, headaches being number one Back pain can result from sudden traumatic injuries, but is more often the result of: –Weak and inflexible muscles –Poor posture –Poor body mechanics during activities

Causes of Back Pain Back pain can occur at any point along your spine Any excessive stress upon the spinal column can cause injury and pain Underlying causes of back pain include: Poor muscle endurance and strength Excessive body weight Poor posture or body position at rest Poor posture body mechanics during activity Previous injuries

Preventing Lower-back Pain Lose weight, stop smoking, and reduce stress Avoid sitting, standing, or working in the same position for too long Use a supportive seat and a medium-firm mattress Warm up thoroughly before exercising Progress gradually when improving strength and fitness Do low-back exercises at least 3 days per week Emphasize muscular endurance Do not do full range of motion spine exercises early in the morning Engage in regular endurance exercise

What Is Body Composition? Body composition is the body’s relative amounts of fat mass and fat-free mass Body fat includes two categories: –Essential fat is crucial for normal body functioning 3–5% of total body weight in males 8–12% of total body weight in females –Nonessential fat is storage or adipose tissue 12-15% in males 20-27% in females

Body Composition

Body Composition of a typical man and woman (20-24 years old)

Defining Overweight and Obesity Overweight is defined as total body weight above the recommended range for good health; range are set by population scales Obesity is defined as a more serious degree of overweight, characterized by excessive accumulation of body fat More than 67% of American adults are now overweight

Problems Associated with Very Low Levels of Body Fat Not considered as prevalent problem as obesity, too little body fat is also dangerous Extreme leanness is linked to the following disorders: Reproductive Circulatory Immune system Eating disorders have been associated with low percentages of body fat, especially in women Bulimia Anorexia Nervosa

Calculating Body Mass Index Body Mass Index (BMI) is a measure that can classify risks, based on the concept that a person’s weight should be proportional to height –Underweight = 18.5 or less –Normal = –Overweight = –Obesity = 30 or greater To determine this, body weight in kilograms is divided by the square of height in meters –BMI = body weight/ height squared –Divide weight by 2.2 and height multiple by.0254 –190 (2.2) / 70 (x.0254) = / 3.16 = Elevated BMI is linked to increased risk of disease, especially if associated with a large waist circumference

The Cardiorespiratory System The cardiorespiratory system transports oxygen, nutrients, and other key substances to the organs and tissues that need them It picks up waste products to where they can be used or expelled

The Heart The heart has the following characteristics: 4 chambers Size of a fist Located just beneath the sternum Arteries carry blood away from the heart Veins carry blood back to the heart The average resting heart rate is between bpm (72 is the standard average)

Heart Rate You can improve your heart rate through cardiorespiratory conditioning. Higher maximum heart rate –You can exercise longer and at greater levels Lower resting heart rate –The heart beats less beats per minute –Can get into the 40’s or 50’s

Resting Heart Rates Males years of age –49-55 is excellent –56-61 is good –62-73 is average Females years of age is excellent is good is average

Maximum and Target Heart Rates –Estimate your maximum heart rate (MHR) 220 – your age = MHR –Multiply your MHR by selecting an appropriate range of 65% - 90% People who are unfit should start at 55% of MHR –Example: 20-year-old MHR = 220 – 20 = % training intensity = 0.65 X 200 = 130 bpm 90% training intensity = 0.90 X 200 = 180 bpm THR then is

Thursday Thursday we will have Quiz I in this room. No working out that day. See you on Thursday!