Clinical assessment of nail and skin lesions in indoor climbers: A clinic-based cross-sectional study

Table 1 Distribution of podiatric lesions by sex (absolute number of lesions)

Podiatric lesion	Female (n)	Male (n)	Total (n)
Hyperkeratosis	323	502	825
Beau’s lines	7	50	57
Longitudinal traumatic ridges	1	30	31
Post-traumatic onycholysis	7	22	29
Subungual hematoma	3	23	26
Splinter hemorrhages	4	14	18
Onychodystrophy	4	7	11
Haglund’s disease	3	9	12
Onychomycosis	0	7	7
Onychomadesis	0	3	3
Onychocryptosis	0	2	2
Warts	0	2	2
Tinea pedis	0	1	1

Data are reported as absolute number of recorded lesions. Multiple lesions per participant were permitted; lesion counts exceed the total number of participants.

Table 2 Distribution of hyperkeratosis subtypes (absolute number of lesions)

Hyperkeratosis subtype	n (%)
Medial periungual hyperkeratosis	260 (31.5)
Lateral periungual hyperkeratosis	192 (23.3)
Pinch callus	95 (11.5)
Submetatarsal head hyperkeratosis	87 (10.6)
Calcaneal xerosis	52 (6.3)
Apical toe lesion	52 (6.3)
Dorsal hyperkeratosis (PIP joint)	32 (3.9)
Interdigital heloma	29 (3.5)
Plantar toe lesion	15 (1.8)
Retrocalcaneal xerosis	6 (0.7)
Lateral skin lesion, fifth toe	5 (0.6)

Digit-level breakdowns for periungual hyperkeratosis are provided in Table 3. PIP: Proximal interphalangeal.

Table 3 Distribution of medial and lateral periungual hyperkeratosis by digit, n (%)

Digit	Medial periungual	Lateral periungual
First nail	85 (32.7)	108 (56.2)
Second nail	58 (22.3)	51 (26.6)
Third nail	53 (20.4)	22 (11.5)
Fourth nail	40 (15.4)	6 (3.1)
Fifth nail	24 (9.2)	5 (2.6)

Table 4 Anatomical distribution of nail disorders by affected digit (percentage within each disorder)

Nail disorder	Total (n)	1st toe (%)	2nd toe (%)	3rd toe (%)	4th toe (%)	5th toe (%)
Beau’s lines	57	48.2	21.4	19.6	7.1	3.7
Post-traumatic onycholysis	29	58.6	13.8	6.9	17.2	3.5
Longitudinal traumatic ridges	31	67.7	12.9	9.7	0.0	9.7
Subungual hematoma	26	80.8	11.5	0.0	3.8	3.8
Splinter hemorrhages	18	38.9	5.6	22.2	22.2	11.1
Onychomycosis	7	50.0	33.3	16.7	0.0	0.0
Onychodystrophy	11	20.0	0.0	10.0	20.0	50.0

Percentages refer to distribution across digits within each nail disorder. Onychomadesis (n = 3) and onychocryptosis (n = 2) affected exclusively the first nail and are not shown separately.

Table 5 Distribution of submetatarsal head hyperkeratosis by metatarsal

Metatarsal head	Total, n (%)
Fifth	48 (55.2)
First	25 (28.7)
Second	9 (10.3)
Third	4 (4.6)
Fourth	1 (1.2)

Table 6 Multivariable negative binomial regression: Factors associated with lesion burden

Variable	IRR	95%CI	P value
Shoe size delta	1.08	1.01-1.16	0.028
Weekly training frequency	1.11	1.02-1.20	0.014
Total weekly training volume	1.05	0.99-1.11	0.081
Age	0.99	0.97-1.01	0.42
Sex (male vs female)	1.06	0.91-1.22	0.45
Body mass index	1.01	0.97-1.05	0.62

All variables entered simultaneously. Variance inflation factor < 2 (no multicollinearity). All statistically significant incidence rate ratios are close to 1.0; findings should be interpreted as exploratory. IRR: Incidence rate ratio; CI: Confidence interval.

Table 7 Summary of key associations between exposure variables and total lesion burden

Variable	Analysis	Effect size	95%CI	P value
Shoe size delta	Spearman ρ	0.195	0.04-0.34	0.015
Shoe size delta	IRR (multivariable)	1.08	1.01-1.16	0.028
Weekly training frequency	Spearman ρ	0.180	0.02-0.32	0.025
Weekly training frequency	IRR (multivariable)	1.11	1.02-1.20	0.014
Total weekly volume	Spearman ρ	0.172	0.01-0.31	0.032
Total weekly volume	IRR (multivariable)	1.05	0.99-1.11	0.081
Session duration	Spearman ρ	0.09	-	0.24
Age	Spearman ρ	-0.03	-	0.68
Sex	Mann-Whitney U	r = 0.06	-	0.41
BMI	Spearman ρ	Approximately 0	-	> 0.05

All ρ values < 0.20 and significant incidence rate ratios close to 1.0 confirm weak effect sizes throughout. IRR: Incidence rate ratio from multivariable negative binomial regression; BMI: Body mass index; CI: Confidence interval.