define muscle endurance

ability to perform repetitive or sustained activities for prolonged periods

what is cardiopulmonary endurance

whole-body dynamic activities while walking, cycling, swimming

what is local muscle endurance

muscles' ability to repeatedly contract, sustain tension, and resist fatigue

characteristics of endurance training

high reps, low intensity, long duration

why is endurance training often better for impaired muscle performance

less joint reaction force, less irritation, more comfortable

what is the overload principle

muscle must be challenged with a load greater than it is accustomed to

how do you apply overload

increase intensity or volume

what is the SAID principle

training adaptations are specific to the demands placed on the muscle

example of SAID principle for power training

increase work demands + decrease time -> explosive movements

what is specificity of training

training effects are specific to mode, velocity, joint position, and movement pattern

example of specificity for stair climbing

use weight-bearing concentric + eccentric training at functional speed

what is transfer of training (carry over effect)

strength training may moderately improve endurance; endurance training does not improve strength

what is the reversibility principle

training effects are not permanent; gains decline without continued training

when does detraining begin

within 1-2 weeks after stopping exercise

what is the role of actin in the sarcomere

thin filament anchored to Z-line; contains binding sites for myosin

what is the role of myosin

thick filament with heads that form cross-bridges; ATP allows detachment and hydrolysis "cocks" the head

what does strength testing assess at the sarcomere level

the ability of sarcomeres to generate tension

what does stretching do at the sarcomere level

lengthens sarcomeres and changes actin-myosin overlap

define concentric contraction

sarcomeres shorten under load; builds strength and power

define eccentric contraction

sarcomeres lengthen under load; builds mass and control

define isometric contraction

sarcomeres maintain length under tension; improves stability and endurance

what triggers muscle contraction at the neuromuscular junction

ACh release -> calcium release -> contraction

what is a motor unit

a motor neuron and all muscle fibers it innervates

what is the recruitment order of muscle fibers

type I -> type IIa -> type IIb

what do small motor units control

fine motor control (eyes, hand intrinsics)

what do large motor units control

powerful force production (glutes, quads)

key characteristics of Type I fibers

high mitochondria, high capillaries, fatigue-resistant, small diameter

what is the function of Type I fibers

postural control, endurance, stability

clinical relevance of Type I weakness

poor postural endurance; common in chronic lower back pain

key characteristics of Type II fibers

large diameter, high force, fatigue quickly, anaerobic

function of Type II fibers

power, speed, explosive movement

clinical relevance of Type II atrophy

atrophy quickly with immobilization, important in rehab

characteristics of Type IIa fibers

fast, moderate fatigue resistance, mixed metabolism

why are Type IIa fibers important in rehab

adaptable toward endurance or power depending on training

characteristics of Type IIb fibers

fastest, largest, highest force, very low fatigue ressitance

function of Type IIb fibers

maximal-intensity, explosive, short-duration movements

what physiological changes occur with strengthening

increased fiber size, neural drive, motor unit recruitment, bone density

what is Wolff's Law

bone remodels according to the loads placed on it

what is the overload principle

load must exceed the muscles metabolic capacity to improve performance

how do you overload for strength

increase load progressively

how do you overload for endurance

increase reps, duration, or time under tension

what is a repetition maximum

greatest amount of weight a muscle can move once through full ROM

what % of 1RM does the average adult train at

75% of 1RM

what is the standard strength protocol

3 sets x 10 reps with load causing fatigue

what is the standard endurance protocol

submax load, 3-5 sets, 40-50 reps OR long sustained holds

what is an isometric exercise

static contraction without joint movement

what is muscle setting

low-intensity isometrics for relaxation, circulation, and reducing spasm

what is stabilization isometrics

isometric contraction in weight-bearing to improve joint/postural stability

what are multiple-angle isometrics

resistance applied at multiple joint angle to improve strength through ROM

standard isometric protocol

7-10 reps, 3-5 sets, 5-7s holds

what is isotonic exercise

muscle changes length while exerting constant force

what are the two isotonic contraction types

concentric (accelerate) and eccentric (decelerate)

what produces more force

concentric or eccentric

what is isokinetic exercise

movement at constant velocity; machine controls speed

what defines open-chain exercise

distal segment moves; non-weight bearing; isolated muscle activation

what defines closed-chain exercise

distal segment fixed; weight-bearing; multi-muscle activation

key precautions for strengthening

pain-free range, avoid breath-holding, avoid ballistic movement, progress gradually

what is DOMS

delayed onset muscle soreness 12-24 hours after exercise; peaks 48-72 hours

absolute contraindications to strengthening

unstable joints, fragile tissue, inflammation, major cardiopulmonary disaese

what is aerobic exercise training

CR endurance training using oxygen-dependent metabolism

what is the Karvonen formula

exercise heart rate = HR rest + 60-70% (HRmax-HRrest)

standard aerobic training protocol

5-10 min warm-up, 20-30 min aerobic, 5-10min, frequency

what are the major effects of disuse on soft tissue

loss of mobility/strength, decreased ROM, altered neuromuscular control, increased stiffness

define contracture

adaptive shortening of musculotendinous & soft tissue -> restricted ROM

what causes a myogenic contracture

adaptive shortening of musculotendinous unit with no underlying pathology

how is a myogenic contracture managed

stretching - static, PNF, prolonged low-load

what causes a pseudomyostatic contracture

CNS lesions or prolonged spasm/guarding

what are key features of pseudomyostatic contracture

constant contraction, excessive resistance to passive stretch

how is pseudomyostatic contracture managed

neuromuscular inhibition (hold-relax, contract-relax, rhythmic rotation)

what causes arthrogenic/periarticular contracture

intra-articular pathology (adhesiosn, synovial thickening, effusion, osteophytes)

how is arthrogenic contracture managed

joint mobilization, stretching, treating underlying pathology

what causes fibrotic/irreversible contracture

prolonged immobilization, severe trauma, chronic inflammation

what are features of fibrotic contracture

dense adhesions, permanent loss of extensibility, severe ROM limitations

how is fibrotic contracture managed

stretching minimally helpful; often requires surgery

define hypotrophy vs atrophy

hypotrophy

what causes atrophy

disuse, immobilization, pain-avoidance, neurological impairment

consequences of atrophy

decreased force production & endurance, altered movement, increased injury risk

what is decreased neurological activity

reduced neural drive -> decreased activation & coordination

effects of decreased neural activity

few signals, delayed stabilizer recruitment, reliance on compensations

define PROM

movement by an external force only; no voluntary contraction

indications for PROM

acute inflammation, post-surgery, paralysis, bed rest

goals of PROM

maintain mobility, minimize contractures, enhance synovial movement, decreased pain

limitations of PROM

cannot prevent atrophy, increase strength, or improve circulation like active movement

PROM contraindications

unstable fracture, unhealed incision, acute muscle tear, DVT

PROM protocol

slow, pain-free, support limb, avoid forcing end-range

define AFROM

movement through voluntary contraction within available range

indications for AFROM

aerobic conditioning, postural strengthening, maintaining mobility above/below immobilized joints

define AAROM

assisted movement when client cannot complete range independently

goals of AFROM

maintain elasticity, provide sensory feedback, stimulate bone/joint tissue, increase circulation, prevent thrombus

limitations of AFROM/AAROM

cannot increase strength of healthy muscle or develop advanced coordination

contraindications for AFROM/AAROM/ARROM

acute inflammation, unstable fracture, post-surgery restrictions, severe cardiopulmonary disease, DVT

ROM progression order

AAROM -> AFROM -> ARROM

what must be documented for PROM

joints moved, range achieved, client response, end feel, rationale

what must be documented for AFROM/AAROM/ARROM

type of ROM, quality, range, strength limits, tolerance, rationale