[Experiment] Prompts for Female Muscle Definition | 14 Conditions, 42 Images

Conclusions First

After comparing 14 muscle expression prompts for women, keywords with clear effects and those without were clearly divided.

Key points:

• muscular and bodybuilder most stably produce strong muscle expression (effective on abs, arms, and legs)
• defined muscles and muscular arms also show stable effects on abs and arms
• toned, athletic, and fitness model show almost no difference from control
• crossfit mainly affects background (CrossFit gym) rather than muscles
• Additional testing: extreme muscular bodybuilder and muscular amazon warrior produce more mass but with ethnicity-change side effects. bulky powerlifter physique adds body thickness as a unique effect. female pro wrestler surprisingly has weak muscle effects
• The ethnicity-change side effect from muscular reported in the full body type guide did not occur in this gym setting

Experiment Design

Base Prompt

full body + sports bra were used to observe muscle changes across the whole body. Bright gym lighting was selected to make muscle shadowing visible.

A00: control (no keyword)

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Observation: All 3 show a slender body type with no visible abs definition or arm muscle prominence. The abdomen is flat but not muscular, and arms/legs are thin. Sports bra and shorts specifications are correctly reflected. Asian female appearance is maintained.

A01: muscular

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Observation: 3/3 images show clearly defined vertical abs (six-pack). Biceps and deltoid prominence visible, shoulders broader than control. Thighs are thicker with visible muscle contour. All 3 maintain Asian female facial features with no skin tone change. One of the conditions with the clearest difference from control.

A02: toned

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Observation: Almost no difference from control. All 3 remain slender with no clear abs definition. Arm and leg muscle are similar to control. toned has a weak effect on body shape in z-image-turbo.

A03: athletic

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Observation: Almost no difference from control. All 3 maintain a slender body type with no notable muscle definition in abs, arms, or legs. athletic may affect movement or atmosphere rather than body type, but no muscle mass change appeared in this still pose.

A04: fitness model

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Observation: Almost no difference from control. All 3 remain slender with no visible abs definition or arm muscle prominence. fitness model appears to be interpreted as model physique (slender, tall) direction rather than increasing muscle mass.

A05: defined muscles

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Observation: 3/3 images show visible abs definition. Deltoid and upper arm prominence also visible. Compared to muscular, overall muscle mass is slightly more modest, with thigh changes in only 2/3. Has a “showing muscles” directional effect. Asian appearance maintained.

A06: bodybuilder

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Observation: 3/3 images show six-pack abs, deltoid and bicep prominence, and developed quads. Muscle mass is comparable to or greater than muscular, with noticeably wider shoulders. 1/3 images (s1) shows a hands-on-hips bodybuilding pose. Asian appearance maintained in all 3.

A07: lean muscle

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Observation: 2/3 images show visible abs definition. Arm muscle shows slight prominence in 2/3, but not as pronounced as muscular. Thigh changes limited to 1/3. Overall a more moderate muscle expression than muscular — more of a “toned body” direction. S1 remains slender and close to control.

A08: crossfit

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Observation: The biggest change is in the background. 3/3 images show CrossFit gym-specific equipment (power racks, wooden wall panels, rubber flooring) — a distinct space from a regular fitness gym. For body type, only 1/3 (s1) shows abs and arm muscle; the remaining 2 are close to slender control. Unstable as a muscle expression keyword.

A09: muscular arms

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Observation: 3/3 images show clear upper arm and deltoid prominence. Abs definition also appears in 3/3 despite specifying only “arms” — muscle expression spread to the full body. Thigh mass increase visible in 2/3. Compared to muscular, arm thickness is slightly more emphasized, though the difference is not dramatic.

A10: female pro wrestler

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Observation: Only 1/3 (s1) shows slight deltoid and quad prominence, but no clear abs definition. S2 and s3 are near-slender and close to control. pro wrestler mainly affects pose (power stance, hands on hips) rather than muscle mass — unreliable as a muscle description keyword. Asian appearance maintained in all 3.

A11: extreme muscular bodybuilder

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Observation: 3/3 images show six-pack abs, notable deltoid/bicep prominence, and developed quads. Muscle mass is comparable to or greater than bodybuilder alone, with particularly developed shoulders and arms in s2. S3 shows a mirror selfie pose with prominent arm muscles. However, 2/3 images show the face drifting away from an Asian appearance — the japanese actress specification is weakened. Increased muscle mass comes at the cost of reduced ethnicity consistency.

A12: bulky powerlifter physique

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Observation: 3/3 images show developed deltoids, upper arms, and quads. Abs definition visible in all 3. Unlike other muscle keywords, the overall body has increased thickness and bulk. Shoulders are wide, thighs are approximately 1.5x thicker than control. S3 shows a double-bicep pose. The emphasis is on overall volume rather than muscle cut definition. Asian appearance mostly maintained in all 3.

A13: muscular amazon warrior

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Observation: 3/3 images show clear abs definition, deltoid/upper arm prominence, and increased thigh mass — comparable to muscular or bodybuilder. S2 shows particularly defined abs and developed thighs. S3 shows a bicep pose with prominent arm muscles. However, approximately 2/3 images show some facial feature shift away from Asian characteristics. amazon may pull toward a Western-looking archetype. The gym outfit setting is maintained — no armor or warrior costume appeared.

Cross Comparison of Extreme Muscle Expressions

Comparing the strong muscle conditions from earlier (muscular, bodybuilder) against the 4 new conditions.

Key observations:

• Token efficiency: muscular (1 token) provides sufficient muscle expression. 3-token extreme muscular bodybuilder increases mass slightly but introduces ethnicity-change side effects
• Body thickness: Only bulky powerlifter physique produces a “thick/bulky” body shape direction. Others add muscle definition but silhouettes remain similar
• Limits of pro wrestler: Pro wrestlers mainly influence pose and atmosphere, not muscle depiction — not suitable as a muscle keyword
• Ethnicity shift tendency: Words strongly associated with Western culture like extreme or amazon tend to weaken the japanese actress specification

Summary

After comparing 14 muscle expression prompts, the following groups can be identified:

Strong effect (muscle consistently depicted):

• muscular — Whole-body muscle mass increase. Effective on abs, arms, and legs. Efficient at 1 token
• bodybuilder — Comparable to or greater than muscular. Bodybuilding pose may appear
• defined muscles — Stable effect on abs and arms. Slightly more modest than muscular
• muscular arms — Specifying arms still spreads to full body. Comparable to muscular
• extreme muscular bodybuilder — Maximum muscle mass but with ethnicity-change side effects. 3 tokens
• bulky powerlifter physique — Adds body thickness in addition to muscle. Ethnicity maintained. OK
• muscular amazon warrior — Muscle mass comparable to muscular but with ethnicity-change side effects

Weak effect (muscle visible in some images only):

• lean muscle — Abs visible in 2/3 but unstable
• crossfit — Mainly background change. Useful for changing gym environment
• female pro wrestler — Moderate muscle in only 1/3. Mainly affects pose

No effect (no difference from control):

• toned — Remains slender with no change
• athletic — Remains slender with no change
• fitness model — Interpreted as model physique (slender direction)

The full body type guide reported an ethnicity/skin-tone change side effect from muscular, but in this gym setting (sports bra + athletic shorts + gym interior), muscular alone maintained Asian appearance in 3/3. However, adding words strongly associated with Western culture (like extreme muscular bodybuilder or muscular amazon warrior) did trigger ethnicity changes.

For muscle definition, using muscular or bodybuilder is practical. For moderate muscle, defined muscles is the best choice. For extreme mass with body thickness, bulky powerlifter physique maintains ethnicity while delivering strong effects.

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