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Abstract

Introduction

Mount Fuji has four-distinct routes, each with unique characteristics. However, no studies have examined how different routes influence falls and related factors during descent.

Methods

We conducted a questionnaire survey of 463 participants who descended Mount Fuji via the Fujinomiya route and compared the results with data from our 2021 study on the Yoshida route (n = 551). The survey collected information on sex, age, height, body weight, luggage weight, experience on Mount Fuji and other mountains, use of a tour guide, single-day climb or overnight stay, awareness of downhill trail conditions (volcanic gravel, long distance, and fall risk), use of trekking poles, shoe type, shoe sole condition, and self-reported fatigue.

Results

The fall rate was higher on the Fujinomiya route (271/463, 59%) than on the Yoshida route (232/551, 42%). Route-specific factors influencing fall risk included interactions between route and trekking pole use, shoe type, and fatigue level. On the Fujinomiya route, climbers not wearing hiking shoes or mountaineering boots had a higher fall risk. However, on the Yoshida route, fall risk was lower in climbers who used trekking poles and reported less fatigue. In contrast, on the Fujinomiya route, fall risk was unaffected by trekking pole use or fatigue level, while on the Yoshida route, shoe type had no impact.

Conclusion

These findings suggest that route-specific precautionary measures may be necessary for climbers on the Yoshida and Fujinomiya routes.

Keywords

fatigue feeling multiple logistic regression rocky area route interaction steep slope trekking pole use shoe type

Introduction

Mount Fuji has four climbing routes: Yoshida, Subashiri, Gotenba, and Fujinomiya. We previously investigated fall prevalence and related factors on the Yoshida route using questionnaire surveys.^1,2 Reported fall prevalence rates were 30%¹ and 40%.² Female climbers, those with less climbing experience, and single-day climbers had increased fall risks.¹ Another study identified additional risk factors, including older age, lack of a tour guide, limited knowledge about descent conditions, nonuse of trekking poles, absence of mountaineering boots, worn-out shoes, and greater fatigue.² Although questionnaire items differed slightly between studies,^1,2 findings suggest that no single factor fully explains fall risk, even on the same route. Approximately 60% of Mount Fuji climbers use the Yoshida route, while about 25% use the Fujinomiya route.³ Fall prevention on these routes is therefore crucial for climber safety. Notably, these routes differ significantly. The descent from the summit to the fifth station varies in distance and average slope (Yoshida: 7 km, 24% slope; Fujinomiya: 4.3 km, 33% slope).³ Additionally, the Yoshida route features a long, gentle descent with gravel, sand, and volcanic ash, whereas the Fujinomiya route consists mainly of steep, rocky terrain.³ Despite the high number of climbers and distinct route characteristics, no studies have compared fall prevalence between them. To address this gap, we conducted a questionnaire survey of climbers on the Fujinomiya route in 2022 and 2023 and compared the results with data from our 2021 study on the Yoshida route.²

Methods

Survey Sites and Participants

The two survey sites were the Fujinomiya (altitude: 2380 m) and Yoshida (altitude: 2305 m) trailheads. This study was approved by the ethics committee of the Mount Fuji Research Institute, Japan, in accordance with the Declaration of Helsinki (ECAE-01-2018). After a detailed explanation of the study, informed consent was obtained from each participant.

At the Fujinomiya trailhead, we surveyed descending Japanese climbers between 08:00 and 13:00 on July 23, 24, 30, and 31; August 11, 15, 20, and 27 in 2022; and on July 24, 25, 29, and 30 in 2023. The number of survey dates was increased compared to the Yoshida route due to the relatively smaller number of climbers on the Fujinomiya route. To ensure data quality, we confirmed that all participants were completing the survey for the first time and had sufficient time (approximately 15 min) to complete the questionnaire carefully before distributing the survey sheets.

Questionnaire

As in our previous study,² we used the same questionnaire sheet (Supplemental Table 1). Briefly, participants provided information on their fall and injury status, followed by (1) age, (2) sex, (3) height, (4) body weight, (5) backpack weight, (6) Mount Fuji climbing experience, (7) other mountain climbing experience, (8) presence of a tour guide, (9) trailhead at a starting point, (10) single-day climb or overnight stay, (11) summit success, (12) information on the downhill trail, (13) trekking pole use, (14) shoe type, (15) shoe sole condition, and (16) a 25-item feeling of fatigue questionnaire (scored 1–5, from “disagree completely” to “agree strongly”), originally developed by Sasaki et al (2005)⁴ and used in our previous studies.^1,2

Data Analyses

Body mass index (BMI) was calculated by dividing the body weight (kg) by [height × height (m)].

Statistical Analyses

Multiple logistic regression analysis was performed to identify key factors influencing fall incidence among participants on the Fujinomiya route (present study) and the Yoshida route (previously published by Uno et al, 2023).² The dependent variable was fall occurrence (0 = no fall, 1 = fall). Independent variables included 16 items, and 15 route interaction items (ie, route × each variable) (Table 1). To minimize multicollinearity, we confirmed that variance inflation factor values for all independent variables were < 4.^1,2 Model selection was performed using backward stepwise elimination based on the Akaike information criterion, incorporating interaction effects between routes.^1,2 If a route interaction was detected, risk factor estimates were determined separately for each route using nested effects in the multivariable logistic regression model.² An unpaired t-test was also used to compare weather conditions between survey days on the two routes. Statistical analysis was conducted using R software (version 4.4.1, Vienna, Austria).⁵

Table 1.

Dependent and Independent Variables for Multiple Logistic Regression Analysis.

		Dummy Variables
	Survey Items	0	1	2
Dependent variables	Fall status	No fall	Fall
Independent variables (category)	Sex	Male	Female	-
	Experience on Mount Fuji	First time	More than twice	-
	Experience on other mountains	Less than 2 years	More than 2 years	-
	Guided tour	Without	With	-
	Stay	Not stayed	Stayed	-
	Information for downhill trail
	Volcanic gravel	Unknown	Known
	Long distance	Unknown	Known
	Fall risk	Unknown	Known
	Pole use	Without	With	-
	Shoe type	Other shoes	Hiking or climbing boots	-
	Route	Yoshida	Fujinomiya
Independent variables (order)	Shoe sole condition	Not worn out	Moderately worn out	Quite worn out
Independent variables (continuous)	Age
Independent variables (continuous)	Body mass index
	Relative backpack weight
	Fatigue feeling

Results

The mean (± standard deviation) weather conditions at the summit of Mount Fuji during the 12 survey days were as follows: barometric pressure 651 ± 4 hPa, ambient temperature 7.9 ± 1.5 °C, relative humidity 68 ± 17%, and sunshine duration 9 ± 4 h on the Fujinomiya route in 2022 and 2023, compared with 647 ± 5 hPa, 7.2 ± 0.9 °C, 68 ± 31%, and 7 ± 6 h on the Yoshida route in 2021. No significant differences were observed between the two routes (all P > .05).

Across the survey days, 614 participants were asked to complete the questionnaire. Based on exclusion criteria from our previous study, 151 responses were excluded due to (i) age <15 years, (ii) starting point not being the Fujinomiya trailhead, (iii) failure to reach the summit, (iv) broken shoe soles, or (v) incomplete responses. This yielded 463 valid responses, with an effective response rate of 75% for the Fujinomiya route. Among these participants, 271 experienced falls (271/463, fall rate: 59%), with 899 recorded falls. Additionally, 124 participants fell more than 3 times, and 41 sustained fall-related injuries (injury rate: 8.9%). These numbers exceeded those on the Yoshida route (fall rate: 42% [232/551], total falls: 741, participants with >3 falls: 100, injury rate: 6.2% [34/551]).² Detailed fall number, motion of falls, and injury status are provided in Supplemental Table 2. Participant characteristics for both routes are summarized in Table 2.

Table 2.

Characteristics of the Surveyed Independent Variables in Males and Females.

	Fujinomiya		Yoshida
	No fall	Fall	No fall	Fall
Sex
Male	140 (73%)	164 (61%)	229 (72%)	132 (57%)
Female	52 (27%)	107 (39%)	90 (28%)	100 (43%)
Age, years	41.9 ± 14.3	45.3 ± 13.9	34.5 ± 12.5	36.2 ± 14.1
BMI, kg (m²)⁻¹	22.5 ± 2.9	22.0 ± 2.7	22.1 ± 2.9	22.1 ± 2.9
% Luggage weight per body weight, %	9.7 ± 3.4	9.7 ± 3.5	9.7 ± 3.2	9.4 ± 3.8
Experience on Mount Fuji
First time	80 (42%)	119 (44%)	198 (62%)	172 (74%)
More than once	112 (58%)	152 (56%)	121 (38%)	60 (26%)
Experience on other mountains
Less than 2 years	65 (34%)	108 (40%)	189 (59%)	150 (65%)
More than 2 years	127 (66%)	163 (60%)	130 (41%)	82 (35%)
Guided tour
Without tour guide	167 (87%)	218 (80%)	254 (80%)	164 (71%)
With tour guide	25 (13%)	53 (20%)	65 (20%)	68 (29%)
Stay
Not stayed	45 (23%)	59 (22%)	38 (12%)	23 (10%)
Stayed	147 (77%)	212 (78%)	281 (88%)	209 (90%)
Information for downhill trail
Volcanic gravel
Unknown	36 (19%)	61 (23%)	116 (36%)	107 (46%)
Known	156 (81%)	210 (77%)	203 (64%)	125 (54%)
Long distance
Unknown	36 (19%)	65 (24%)	117 (37%)	120 (52%)
Known	156 (81%)	206 (76%)	202 (63%)	112 (48%)
Fall risk
Unknown	20 (10%)	30 (11%)	79 (25%)	87 (38%)
Known	172 (90%)	241 (89%)	240 (75%)	145 (62%)
Pole use
No	57 (30%)	84 (31%)	106 (33%)	89 (38%)
Yes	135 (70%)	187 (69%)	213 (67%)	143 (62%)
Shoe type
Other shoes	10 (5%)	35 (13%)	27 (8%)	30 (13%)
Hiking or climbing boots	182 (95%)	236 (87%)	292 (92%)	202 (87%)
Shoe sole
Not worn out	71 (37%)	86 (31%)	204 (64%)	129 (56%)
Moderately worn out	88 (46%)	121 (45%)	106 (33%)	90 (38%)
Quite worn out	33 (17%)	64 (24%)	9 (3%)	13 (6%)
Fatigue feeling	40.8 ± 14.3	40.5 ± 13.6	46.1 ± 15.9	53.3 ± 15.9

For the categorical variables, the number of participants belonging to different categories and their proportions (in parentheses) are shown. When analyzing, set the top category to 0 and the bottom to 1. For continuous variables, values are represented as the means ± standard deviations. BMI, body mass index.

The prediction model identified 13 variables influencing fall risk, including sex, age, Mount Fuji climbing experience, guided tour participation, information on long-distance descent, shoe sole condition, “route × trekking pole use,” “route × shoe type,” and “route × fatigue” (Table 3). Figure 1 further illustrates the interaction effects identified in Table 3, comparing the Fujinomiya and Yoshida routes.

Figure 1.

Interaction Effect for Probability of Falls Between the Fujinomiya and Yoshida Routes.

Table 3.

Summarized Results of Multiple Logistic Regression Analysis Using Backward Stepwise Method.

			95% CI
		OR	Lower	Upper	P values
Variables
Sex	Male
	Female	1.979	1.485	2.635	<.001
Age		1.510	1.291	1.766	<.001
Experience on Mount Fuji	First time
	Two times or more	0.690	0.509	0.937	.017
Guided tour	Without guide
	With guide	1.443	1.032	2.017	.032
Information for long distance	Unknown
	Known	0.567	0.413	0.780	<.001
Trekking pole use	Non-used
	Used	0.575	0.385	0.858	.007
Shoe type	Other shoes
	Hiking shoes or mountaineering boots	0.766	0.415	1.414	.394
Shoe sole condition	Not worn out
	Moderately worn out
	Quite worn out	1.170	1.017	1.348	.029
Fatigue feeling		1.493	1.244	1.793	<.001
Route	Yoshida
	Fujinomiya	3.484	1.356	8.950	.010
Route × Trekking pole use	Yoshida × Pole
	Fujinomiya × Pole	1.607	0.893	2.894	.114
Route × Shoe type	Yoshida × Shoe type
	Fujinomiya × Shoe type	0.396	0.148	1.059	.065
Route × Fatigue feeling	Yoshida × Fatigue	0.644	0.483	0.859	.003
	Fujinomiya × Fatigue

OR, odds ratio; CI, confidential interval. The numerical values of 95% CI indicate those of OR. These analyses used standardized data.

Discussion

Fall Prevalence of the Two Routes

Although the fall rate on the Fujinomiya route (59%) appears high, previous studies on the Yoshida route reported 30%¹ and 40%.² The higher fall rate on the Fujinomiya route may relate to route-specific terrain, footwear, and participant demographics. Notably, in our survey, over 80% of falls occurred during descent (Supplemental Table 2). Similarly, Faulhaber et al (2017) reported that 75% of documented fall-related accidents in the Austrian Alps occurred on descent.⁶ Although their retrospective accident data cannot be compared directly, both studies consistently highlight descent as the most vulnerable phase.

Interaction Effect of Different Routes on Fall Risks

On the Fujinomiya route, fall risk was associated with shoe type—climbers who did not wear hiking shoes or mountaineering boots had a higher risk of falling (Figure 1A, left). In contrast, trekking pole use and lower fatigue levels did not reduce fall risk on this route (Figure 1B, C, left). Previous studies have reported that shoe-ankle orthoses, which stabilize ankle motion and positioning, improve balance in older adults and may help reduce fall risk.⁷ These orthoses typically extend higher up the lower leg (eg, near the soleus muscle), resembling hiking or mountaineering boots. While the precise mechanisms remain unclear, improved stability may provide greater benefits on rocky, uneven terrain with steep slopes, such as the Fujinomiya route, compared to sand and gravel trails with gentler slopes, like the Yoshida route. Since trekking pole use is known to reduce muscle damage during descent,⁸ the finding that trekking poles did not lower fall risk on the Fujinomiya route was unexpected. A possible explanation is that the rocky, stairlike terrain with large steps on this route makes effective pole placement difficult. Climbers may struggle to plant their poles securely due to the uneven surface and often need to place them farther ahead, making it challenging to maintain stability as the pole position moves away from the body's center of gravity. Although both physical⁹ and mental fatigue¹⁰ are recognized risk factors for slip-induced falls, the current interaction findings may be controversial because lower fatigue levels were associated with lower fall risk only on the Yoshida route (Figure 1C, right).

This may be influenced by the longer Yoshida descent compared to the Fujinomiya route (7.0 km vs 4.3 km). Additionally, as shown in Table 2, a greater proportion of climbers on the Yoshida route were novice climbers compared to those on the Fujinomiya route (67% vs 43%, regardless of no fall or fall). These factors could contribute to the fatigue-related fall risk differences between routes. However, as the survey was conducted postclimb, with potential variability in the timing of falls and self-reported fatigue, further research is needed to clarify these interactions.

Common Factors Influencing Fall Risks on Both Routes

This study identified several common factors associated with higher fall risk, regardless of terrain differences between the Fujinomiya and Yoshida routes (Table 3). These included female sex, older age, limited climbing experience on Mount Fuji, guided tours, lack of information on descent distance, and poor shoe sole condition. In general, females and older adults tend to have lower muscle volume, which can contribute to higher fall risk. Indeed, a previous study reported that fall risk increases with age and is higher among females.¹¹ Interestingly, limited experience on Mount Fuji, but not on other mountains, was associated with higher fall risk, regardless of the route. Since mountain climbing requires both ascent and descent, it presents unique challenges for novice climbers or those with limited trekking experience.⁹ This finding suggests that Mount Fuji may pose specific risks for first-time climbers, potentially due to its distinct terrain and descent conditions.

Surprisingly, climbers with a tour guide had a higher fall risk on both routes. Since preferred walking speed on rough terrain varies among individuals and is slower than the cost-of-transport minimum speed,¹² it is still possible that guided participants may have been forced to walk at a pace that differed from their preferred speed, leading to greater energy expenditure, fatigue, and finally fall risk. Additionally, less experienced or less fit individuals may be more likely to join guided groups due to perceived difficulty or safety concerns.¹³ However, our multivariable analysis controlled for confounders, and multicollinearity diagnostics (variance inflation factor <4.0) confirmed that guide use and first-time climbing status were not strongly correlated. Therefore, the increased fall risk among guided climbers cannot be solely attributed to inexperience. A previous study reported that not knowing the remaining distance during a leg cycling time trial can lead to increased muscle fatigue and impaired judgment.¹⁴ Similarly, when the remaining distance was longer than expected, perceived exertion increased and power output declined compared with known distance conditions.¹⁵ These findings support the idea that unknown descent distance may contribute to fall risk. Thus, posting distance markers along the trail may help mitigate this risk. Since shoe sole tread groove depth¹⁶ influenced the coefficient of friction, which may increase fall risks, our findings were reasonable. The results support the idea that wearing well-maintained or new shoes could help reduce fall risk, whether on the gravel, sand, and volcanic ash of the Yoshida route or the rocky terrain of the Fujinomiya route.

Methodological Considerations

Differences in climber demographics, including reporting or selection bias between the Yoshida and Fujinomiya routes, should be considered when interpreting the comparison results. However, directly comparing fall rates and related factors in the same climbers is nearly impossible. Most climbers—except for tour guides—typically climb Mount Fuji only once per summer season, making it impractical to track the same individuals over multiple seasons. Additionally, following up with climbers in subsequent years is unfeasible due to privacy constraints, as personal contact information (eg, postal address, phone number, or email) is not collected. Although weather conditions did not significantly differ between survey days on the two routes, we cannot completely rule out the influence of slight variations in barometric pressure, ambient temperature, relative humidity, or sunshine duration. However, since weather conditions cannot be controlled, minor differences are inevitable. Future research could compare fall risk factors on other mountains with similar descent surfaces, such as gravel/ash trails versus rocky terrain, to assess whether the route-specific interactions observed on Mount Fuji are generalizable to broader hiking populations and environments.

Conclusions

On both the Yoshida and Fujinomiya routes, higher fall risk was associated with female sex, older age, limited climbing experience on Mount Fuji, guided tours, lack of knowledge about descent distance, and poor shoe sole condition. Additionally, on the Fujinomiya route, not wearing hiking or mountaineering boots increased fall risk, whereas trekking pole use and fatigue level did not influence fall risk. These findings suggest that route-specific precautionary measures may be necessary to help reduce fall risk for climbers on both routes.

Supplemental Material

sj-docx-1-wem-10.1177_10806032251387527 - Supplemental material for Differences in Influencing Factors for Fall Risks During Descent on Mount Fuji: A Comparison of the Fujinomiya and Yoshida Routes

Supplemental material, sj-docx-1-wem-10.1177_10806032251387527 for Differences in Influencing Factors for Fall Risks During Descent on Mount Fuji: A Comparison of the Fujinomiya and Yoshida Routes by Tadashi Uno, Satomi Mitsui and Masahiro Horiuchi in Wilderness & Environmental Medicine

Supplemental Material

sj-docx-2-wem-10.1177_10806032251387527 - Supplemental material for Differences in Influencing Factors for Fall Risks During Descent on Mount Fuji: A Comparison of the Fujinomiya and Yoshida Routes

Supplemental material, sj-docx-2-wem-10.1177_10806032251387527 for Differences in Influencing Factors for Fall Risks During Descent on Mount Fuji: A Comparison of the Fujinomiya and Yoshida Routes by Tadashi Uno, Satomi Mitsui and Masahiro Horiuchi in Wilderness & Environmental Medicine

Footnotes

Acknowledgments

The authors thank all participants for their time and effort. The authors thank Chieko Takiguchi, Mie Matsuyama, and Yasuhiro Tsukada for their technical assistance in collecting data.

ORCID iD

Masahiro Horiuchi

Author Contribution(s)

Tadashi Uno: Conceptualization; Data curation; Formal analysis; Investigation; Methodology; Project administration; Supervision; Writing – original draft; Writing – review & editing.

Satomi Mitsui: Conceptualization; Data curation; Formal analysis; Investigation; Methodology; Project administration; Writing – review & editing.

Masahiro Horiuchi: Conceptualization; Data curation; Investigation; Methodology; Project administration; Writing – original draft; Writing – review & editing.

Financial/Material Support

This study was supported by a grant from the Japan Society for the Promotion of Science (KAKENHI, no. 20K12450 to TU).

Disclosure Statement

The authors declare no conflict of interest related to this study.

Supplemental Material

Supplementary material associated with this article can be found in the online version at .

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Supplementary Material

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